Serious use of the BP6 with seriously sized drives means the bad joke of the HPT366 controller gets retired to READ-ONLY device operations . A Promise/Maxtor ATA100 or 133 PCI controller card will solve your problem. It is really worth the $30 investment! Hope you have a free slot!
When halflunatik says just use HPT366, he means let the BIOS misdetect the drive & then wait for the OS to load & figure out the correct drive parametes. This seems to be working for him with Win2K-Server. I would advise avoiding this approach - even if it does work with your Deskstar 120G.