Computer help: Very, Very , Very BAD computer Problem.

Very, Very , Very BAD computer Problem.

First my Computers Config
My 1 st computer
Pentium Celeron 333
8.4 GB HD
Win 2k
Win XP
128 MB RAM
Win 2K on NTFS
Win XP on FAT 32
2 Partitions

My 2nd Computer

Pentium 4 1.5
40 GB HDD
Nvidia TNT2 32 MB VRAM
256 MB RAM
Win XP on NTFS
Win XP on NTFS
No Partition

Now my problem is this:

My 2nd computer and my first computer used to running fine.

Suddenly one fine day I switch on my 2nd computer and both the OS's give me a Stop error (I had installed one of them to boot and access to my data). So I tried to put the 40 GB HD in the first comp, but the 1st comp does not support large hard disks.

So i tried to put the old 8.4 GB Hard Disk in the new one and it gives me a stop error when I try to boot into 2K. So I installed XP on FAT 32 to access the 40 GB HD. I then tried to boot into it without the new (40 GB HD), and it booted, but when I connected the new HD as a slave, it just refused to boot, as in XP on 8.4 HD just keeps loading without any further progress. When I connected the new HD as Secondary Master, it boots, but then it does not access the new HD. When I try to access the old HD it says it is to be formatted. When I try to install XP on the 40 GB HD, it tells me to format the partition.

I tried to boot in safe mode but it gives me the same error, bt it shows that all the files are loading. The XP boot screen appears, my data is important, what do I do to retrieve the data from my 40 GB Hard Disk?