I found a solution that worked for me
I'm going to post the long version of this for any Googler's out there looking for a solution to this.
For the speed demons out there, scroll down to the section titled "SOLUTION".
I hope someone can find an easier solution than this, but here's what I had to do.
We had a similar scenario here. We have a network with 6 PCs. 3 are Windows XP x86, 2 are Windows 7 x64, and 1 is Windows Server 2003 x64. The Epson Photo Stylus R200 was connected to one of the WinXP machines.
Everything was working fine until we had a power outage this weekend. Now the WinXP PC that was hosting the printer will not come on. We get a series of beeps which = bad. The next most practical PC to host the printer is the Win7 PC that is also right next to the printer. The other PCs are much further away.
We connected the printer to the Win7 machine, downloaded the Win7 x64 drivers from the Epson website
here, installed them, tested the printer... everything works great.
Next step: install on other Windows 7 machines. Installs great over network. Works perfect.
Next step: install on WinXP machines. It failed on each one.
Let me add this little tidbit first- With network printer sharing in Windows, there are 2 ways to install the printer driver when you add the printer manually:
1: Either the host computer (PC hosting the printer) can serve up the driver, or
2: You can install the printer manually on the local PC (the PC connecting to the printer over the network)
If the host PC has a driver available that matches the needs of the local PC, Windows will transfer the driver automatically for you. If not, Windows will prompt you to install it.
So on each of the WinXP machines, the setup would prompt me to install the driver myself. This made sense to me, because I didn't think that the Win7 x64 driver on the host PC was going to work on WinXP x86 machines. So it asked for me to choose one.
I went back to the Epson website and got the appropriate WinXP x86 drivers
here.
Side Note: These drivers from Epson are a little annoying to me. Because instead of giving me a ZIP file that I can unpack and save somewhere, they are self-extracting ZIPs. They unpack to some obscure location, then auto-runs the installer. And just when you think you're actually going to get to the files.. nope, it unpacks ANOTHER setup.exe file that then unpacks ANOTHER set of files.

It starts the printer installer program that starts trying to find your printer. Once this starts, you can get to the real actual files here (WinXP):
C:\Program Files\EPSON\PrinterDriverTemp\SPR200
or here (Win7):
C:\Program Files (x86)\EPSON\PrinterDriverTemp\SPR200
THIS LOCATION IS VERY IMPORTANT. YOU WILL NEED THESE FILES FOR THIS SOLUTION.
From the local WinXP machine, I went to Printers and Faxes (can get to from Control Panel), clicked to Add Printer, selected Network Printer, searched, and selected the printer from the list.
Another side note: If the printer isn't in the list, STRONG chance you've got some sharing issues in Win7. In Win7, from Start>> Control Panel>> Network and Internet>> View Network Status and Tasks, click the network type under Active Networks, select the Home or Work, and make sure the settings are allowing printer sharing and such. May require a reboot after updating (which is never a bad idea anyway).
After selecting the printer, it told me that I didn't have the right driver as I mentioned above. So this time I pointed it at the "PrinterDriverTemp\SPR200" folder above, full of confidence that everything would work.. and... FAIL. I got this error kind of like this:
Cannot find the driver for Epson Stylus Photo R200 (M) in this location.
Um... WTF? I re-verified my download from the Epson website. It was good. I checked several other things I thought could be it, but nothing was it.
Ok then, so I went back to the Win7 host PC to see if there were some sharing issues. I clicked on Start>> Devices and Printers. I right-clicked on the Epson printer, and selected Printer Properties. I then selected the Sharing tab. "Share this printer" is checked. "Render print jobs on client computers" is checked. I updated the name of the printer just for kicks and rebooted. No luck. Same outcome.
Then I noticed that the Sharing tab has a button for "Additional Drivers". There is an option in there for x86 computers. I checked it and hit OK. It then prompted me to select the location of the x86 drivers. Just for completeness sake, I went back to the Epson website, redownloaded the WinXP drivers. Went through the stupid unpacking process again which I cancelled after the files were copied. Then I pointed the "Additional Drivers" driver dialog to that folder, and hit OK. I got (basically) the same error on the Win7 machine as the WinXP one:
"The specified location does not contain the driver Epson Stylus Photo R200 (M) for the requested processor architecture."
SOLUTION
In the folder I mentioned above (where the Epson driver files unpacked), there is an .INF file. "E_DF18HA.INF" to be exact. And, basically, INF files describe to Windows how to install something. They are just text files, they can be easily opened in any text editor.
It appears that Epson has mis-labled the Epson Photo Stylus R200 in their download package. In the INF file, lines 23-25 are this:
[EPSON]
"EPSON Stylus Photo R200 Series" = EPNDRV,USBPRINT\EPSONStylus_Photo_R2C5C0
"EPSON Stylus Photo R200 Series" = EPNDRV,LPTENUM\EPSONStylus_Photo_R2C5C0
This is more or less meaningless, or should be, and should be seemless. But Windows is looking for "Epson Photo Stylus R200 (M)" and it finds "Epson Photo Stylus R200 Series".
So what I did, which is probably obvious at this point, was to change the word "Series" to "(M)" on both lines. The new lines 23-25 were now this:
[EPSON]
"EPSON Stylus Photo R200 (M)" = EPNDRV,USBPRINT\EPSONStylus_Photo_R2C5C0
"EPSON Stylus Photo R200 (M)" = EPNDRV,LPTENUM\EPSONStylus_Photo_R2C5C0
I saved edits, re-browsed to the INF file, hit OK, and it accepted it!
I got a "Windows Can't Verify Publisher" message, but I hit continue. I knew the files came from the official Epson website, so I wasn't concerned. After the continue, the computer sort just sat there for a minute, but then it eventually (2 minutes) finished everything.
I was on the Win7 machine hosting the printer at this point, under the "Additional Drivers" section on the Sharing tab of the Printer properties dialog for the Epson R200 adding a driver for x86. I wanted the host PC to be able to serve up the drivers to the networked PCs.
After this successful installation on the Win7 machine, I was able to go to the WinXP PCs, add the printer, and the driver was installed automatically for me from the Win7 host. It also installed seemlessly on the Win2003 Server x64 PC as well.
I have not tried this text edit on a WinXP machine. The manual install might work there after making this edit, but I don't know.
I don't know why Epson's driver file is jacked up, but the little edit worked!