Hi now I understand.
Item 6 aboveOn your network if you download a driver for this printer on your PC1 machine it will probably be for Windows XP which is what you have on your PC1. hence the error code when you try that driver on the Win 7 PC (PC2)
Item 7 Above,. The driver built in to Windows 7 does not appear o have the Print preview facility in it.
I would suggest that if it works then leave it alone. I think this is an older printer, that model looks as if it has been around for a few years now so that's why there doesn't appear to be a dedicated Epson Win 7 driver. I would live with pressing Print Preview as and when you need it if I were you!
EDIT: I have just done a bit more checking and find that this printer came out in the days of Winows 95 so it is getting a bit long in the tooth. I think you are lucky to get it working at all in Windows 7