Windows 7: Old working slave drive no longer showing up

I recently upgraded windows 7 to x64, and now my slave drive is no longer showing up in My Computer. It shows up in the bios, and in Disk manager.

I have tried assigning it a drive letter, but my only option is "help." I have tried uninstalling the driver for it, then restarting, and reinstalling the driver, but it seems like it auto-installs the driver on startup because when i go back into properties, it says its already installed.

I know I can format it to get it to work again, but I have over 300gb worth of stuff on there I don't want to lose.

INFO:
drive is a Western Digital 640gb Caviar Blue
Running Windows 7 Ultimate x64
drive worked before on windows 7 x86
screenshot of disk manager here

Is there any way for me to get this drive working again without formating?

Hi AOTA

Can you tell us the make & model of your slave HD ? IDE or SATA ?

Also a screen snip of Disk Management will help, too

Yeah, I forgot about that. see my above post for the updated info.
also, model # is: WD6400AAKS
Drive is SATA

I am trying to figure out why this HD is showing up as

Healthy (Active, Recovery Partition )

which seems to mean that it is hidden

Yeah, I noticed that. I dont remember it being that way before, and have not found any way to make it not be set as a recovery.

I remember when I was upgrading, I had some issues, and had to install x64 using the custom (advanced) option. When it came up with the screen asking which partition to install to, the slave drive was first on the list, and there was an error below it saying that windows could not install to that drive b/c is was a recovery disk, even though I had just been using it now 10min before

Are the other 2 HD's SATA or IDE ? I'm thinking that HD needed to be disconnected during the install

One is SATA the other is an external HDD so im not sure.

does this mean I can re-install Windows 7 just make sure the drive is disconnected? or does it mean I am stuck with this drive since I had it connected during installation?

I'm not real sure at this point. I think we need to get some other members opinions on this.

The way I see your Disk Management is that your 640gb Sata HD is connected to your MB as Disk 0.

Your Boot (C Sata HD is connected to the MB as Disk 1.

Your Ext HD is Disk 2.

Are you comfortable with possibly changing the SATA Data cables ? Because I'm thinking the Boot HD should be on Disk 0, but I don't want to loose anything on the 640gb if it can be saved.

OK, so i switched around the cables, and now its kind of working... a new drive is now showing up, with the drive letter of the original, but its not showing up in disk manager, and the original slave drive is still there without a letter.
see here for a better idea of what im talking about

EDIT: the "system reserved" drive is showing up in disk manager as a partition on drive c:
however, the slave drive is still not showing up in my computer, and will not let me assign a drive letter to it.

E: is now showing as the Un-hidden 100mb partition that is normally created by a Windows 7 install. Which is showing as the 1st partition on Disk 0 now. What happens when you right click on the 640gb HD now ?