Drive Recognized but not both partitions

Hello, I've got a PC that I've had running for quite a while with a foxconn motherboard 6150 and a AMD 64 processor and a 32 bit Vista Home ed. I got wild and crazy and upgraded it to a AMD Phenom Quad with a new Gigabyte motherboard and 4 gig of ram. It's a nice enough system and Vista popped up all right and everything is fine except...

The old Foxconn board had two IDE channels and two Sata Channels which I had fully populated. The new board has one IDE channel and 6 Sata Channels. I've installed my two Sata drives to SATA 0 and SATA 1 - seemed like the thing to do. I've got my old IDE drives C: and D: on the one IDE channel and I've ordered a couple of DVD-rom SATA drives so that I'll have some optical readers/storage. When I look at the Sata Drives I see both of the drives and can access files on both. What I don't see is one of the partitions on one one of the drives. Its a 250 G WD and I only see half of it? I wouldn't much care except that there is some data on the missing partition that I'd like to keep. In the scope of the free world it wouldn't be earth shaking to lose this data but it would save me some time to get it back and I'd like the space. Any suggestions? Many Thanks in advance.

PS It occurs to me that I may have swapped the drives, put the old SATA0 drive on the SATA1 Channel and vice versa. I'd thought that the partition markers are actually on the drive media and the order of the drive wouldn't matter much (except if there was a program that addressed a location).

PPS Second Dumb Question: I know that to use the Phenom as a 64 bit processor, I've got to get a 64 bit copy of Vista (I shudder to think of it). Will software that can access the Quad processors do so with the 32 bit operating system or do I need the 64 bits to take advantage of the multiple processors.