Compaq 5000 xp problem PLZ HELP

here it goes my computer needed an overhaul so I formatted the hard drive it is a compaq 5000 had win xp pro on it. I dont know where to find out what motherboard i have in it. My husband knows more than me and did most of this stuff . anyway when I went to reinstsall xp it kept saying NTLDR is missing and couldn't open drive multi(0)disk(0)rdisk(0)partion(1) Me and my husband have been all over forums and have tried many things for the past 3 days. we installed win 98 still error when trying to upgrade to xp. We installed win 2000 pro the same error. finally we took my hard drive out plugged it into his computer put on xp home edition dl some bios program for compaq then tried to plug it back into mine and it goes past the compaq screen then does nothing just a blinking cursor. If anyone has some suggestions to help keep our sanity and so i can get back to playing Aliens VS prdator 2 online It would be fantastic Please Help Me lol.