Does your BIOS show 3gigs of RAM? If so there are a couple of switches that you can add to certain windows boot files to get the OS to see all 3gigs. I had that problem recently with one of my servers, and the fix listed on M$'s technet.com worked great.

As far as the hard drive, what I do is run 2 drives in a RAID0 config that basically doubles my access time since the two drives work as one. I am just guessing here, but it may be a registry issue... there is some pointer that is looking for something on D when it is installed on C, or something like that.