i need computer help (advanced)

[DataXUnknown]

First I will list my problem.

My computer, now, will only boot up if i reset the cmos on the motherboard. Otherwise it doesn't do anything, not even the beep. I tried resetting my memory and that didn't do anything.

The goal I was trying to reach was to reformat.

I have an AMD Athlon 64 Dual Core 5800+Ghz. I am running currently Windows 64-Bit. I DO NOT WANT 64 bit because there is so much confusion for me and installing games and programs, somtimes not being compatible with 64 bit. SO I just want to install Windows XP Professional.

As I put in the CD and change my bios boot sequence, I try to boot from the CD and I click a button to boot from CD and it just continues booting up windows 64 bit. I messed with the boot sequence a little bit more, and then the problem came where I couldn't boot up my PC any more unless I jump the mobo.

Now I'm curious wtf happened and how do I fix it, and put windows xp pro on?