Unable to boot to XP or 2000

I recently assembled a new PC (P4 3.2GHZ, M/B Asus P5GD1 LGA 775, PowerColor x600xt Graphics card, Geil DDR 512MB). I used my old hard disk (Seagate ST340014A 40GB) which is the one I’m using on my other PC. I have a dual boot config on this hard disk (XP and 2000). When I bootup my new PC, I reach bootloader, and from here I could choose which OS to boot. But everytime I boot to XP, my PC restarts. If I boot to 2000, I get blue screen (Inaccessible Boot Device) and I have to restart again. I can see in BIOS setup my hard disk is detected. I also confirmed my hard disk is working by trying it again in my old PC. I changed IDE cable also but still the same problem. Is this just BIOS setup problem? Have any one experienced this?