Problems replacing asus a7n8x-la mobo

i am replacing a mobo asus a7n8x-la like for like swap an have hit problems.got the compaq screen up with bios or system recovery options,then i got the message wrong boot device in use.so rebooted this time i got the screen xp home edition or xp recoevery.clicked on xp then blank screen for ages.so i rebooted an got into bios went change boot options then it frooze.rebooted with xp disk was being read but nothing happerned?????
am confussed what did i do wrong?should i of reset the cmos settings?did i configure it wrong an cause an irq conflicted.do i need to reinstall xp?????
please help!!!!!!!!! thx

thx for the reply.i was going to do that but it kept freezing on me.i replaced a mobo today an the xp booted up ok.but i resetted the cmos jumpers this time.i think if i would of done that on the asus mobo i think i wouldnt of had the problems i did.thx again for the reply.