Im running vista right now, and usually I have no problem switching between Operating systems.

I have my Hard drive partitioned into 2 sections

C: =OS and programs
D: =Back up

Now, when I put my vista disc in, it recognizes the drives, but when I put my XP disc in, it doesn't read the backup partition, it just reads the HDD as one entire partition.

(Though The last time I tried, it came up as C (NTFS), which is correct, and D(unknown) but it should not say that, It's NTFS as well..)

I used the Vista partitioning tool to do this since Partition magic doesn't work in vista too well. I really can't afford to lose the things on my back up partition, I already did once, but managed to recover most of the files. What should I do?

They're not lost if Vista can recognize them. I'd suppose that this was some difference between the Vista and XP versions of NTFS (just a hunch on my part).

To install XP, I'd suggest that you create a new partition (while in Vista) that's in the free space on the C: drive - then install XP to that.

Thats a good idea.. Im trying not too dual boot. But right now the only logical move would be to do so. My understanding is that it is best to install xp first, then vista. Thanks Usasma, not the first time you've helped me .

I had a similar problem. Vista and XP. Talking to other people on other forums it may have something to do with no 3rsd party raid device with SATA drives. I fixed it by reinstalling windows xp without 3rd party raid setup. It worked.