please help! hard drive failure

well, earlier it did recognize it in post (or at least i think it did); i went to BIOS and it showed the primary master is the 200 gig; but it just wont boot up the os

ok, this computer was custom built (obviously not by me as u can tell from my question )
it's a pentium 4;
motherboard L4VXA2
windows 2k pro
has 3 HD (all western digital): primary HD is 200 gig WD2000JB-00EVA0(divided into 2 partitions); 2nd and 3rd are 250 gig each
it has 1 gig of DDR RAM

let me know what other specs you need

thanksa lot for your help

i'm really disappointed in WD; this is the second time it fails on me within less than 3 months; actually, i believe this is the replacement HD that i got from the first one that went bad!

no i haven't yet; i went to their site and dl a few diagnostic tools but havent had a chance to run it yet; i assume that the diagnostic tool is OS independent b/c at this point, the primary disk is the one in trouble on that computer.

i have question tho dustyjay about your suggesting hooking it up as a slave on the working computer; shouldnt i hook it up as a master on the working compuer (since it was the master and primary on the other one) or it doesnt matter?

earlier, i hooked it up to the working computer as a master on a ultra ata pci card and i saw the D partition of it on partition magic; i tried to do a chkdsk and it gave me an error msg about something cross linked error and then froze; i rebooted and then it didnt see that HD any more

i just went and bought a 160 gig seagate to setup as the primary HD; then i can test the bad HD with the utilities once i install win2k completely
but earlier when i had the bad HD as master, it was recognized during POST; so may be the disk is not completely gone yet, hopefully

oh no no, i will use the WD utility to test the WD drive, but i have to get the seagate to be up and running first tho; it's being formatted and installed win2k on it;takes forever
during post, it sees 160 gig, but during installation, it seems to only see about 128 gig, so i guess i might have to run the software from their cdrom in order for the OS to see the full 160 gig.

oops; i didnt use the cdrom before setting up win2k; i guess it's too late for that; it's prob. ok to do it afterwards as well, hopefully