going back

I put Vista in last night over XP and have been unimpressed with how slow and ungainly it is. I know Microsoft still has lots of performance tweaks to put in and all but I'm not willing to blow so much of my time on this right now.
so I want windows XP back.
Problem is, that windows Somehow seems to have taken over the space between Bios and O.S. load, because even though I've gone into the bios and changed ALL of my start up drives to CD Rom and have my XP (and 98) CDs in the drives, Windows continues to boot.
I have three HDs, a SATA2 which Windows is on as my primary and two IDEs. any suggestions for how I'd go about getting Windows XP back if I can't boot to a CD?

hi i'm trying to get xp back i dont want vista anymore but i dont know how to go back..i have the Restore cd from dell and the full xp pro cd too..i want to format the hard drive...i did a clean up and not a upgrade when i installed vista..when i start windows it goes to windows boot maanger ...it can't find file\$windows.bt\windows\system32\winload.exe