If you are using the XP install on the 2nd drive to use these forums, etc, then that XP sees it's own drive as C and any other HDD as D, E, etc. That's by design as Windows works best when it considers it's drive as the primary drive.
So, you could format the D drive, but here's the problem. When you installed XP onto the 2nd drive you setup a boot.ini on the C drive, (the 1st drive that the BIOS sees as the Primary drive), to enable dual boot. Dual boot needs to know which OS is where, and stores that in the boot.ini file on the first bootable drive. If you format that drive, (either using some system disk floppy for the C drive, or from within the workable XP and pointing to D), you will delete that boot.ini and that will make your workable XP install unbootable.
That's where my knowledge ends. I could suggest swapping the drives around so that what is now D becomes C, the bootable drive, then reinstall XP on it, then format the old C drive from within Windows. But my knowledge there is pretty slim and I would guess you need to change jumpers, or so on.
May be others here will know more.
Really struggling to pull this machine back from the brink.
The start of the problem began on Thursday..... When the machine was turned on, all looked well, until just after the Windows opening screen the screen went black and hung.
Tried Safe mode, but will not boot
Tried Last Known Good Configuration, but failed to improve
Tried to boot from CD, but failed.
I managed to Install XP onto the secondary drive and thus log onto this forum.
I have also managed to acces the C: drive and salvage all my data.
I carried out dskchk with no problem.
My next thought was to re-format the Primary drive and go for a clean install. But at present C: is showing it is a system drive and the D: is a boot drive in the Computer Management tool.
If I format C: will I still be able to boot up?
Can anyone suggest a course of action?
System: Windows XP Home Service Pack 2, 2002
Mother board AS Rock AM2NF6G-VSTA
AMD Athlon 64 x 2 Dual
Core Processor 5600+
2.92 GHz,960 MB of RAM
PS There were problem with this machine a couple of months ago that eventually were cured by pulling one of the banks of RAM and a clean install. I havnt replaced tha RAM yet, but would if I can cure the current issues.