Installing XP Over Vista?

hi.. i really dont think this is possible.. BUT, when i put my XP CD in.. and go to the welcome atuo run whatever screen.. "install XP" isn't highlighted and is unable to click.. and it's becuz i have Vista.. Well My computer doesn't boot up CD for some reason (yes i know.. go into BIOS... show more hi.. i really dont think this is possible.. BUT, when i put my XP CD in.. and go to the welcome atuo run whatever screen.. "install XP" isn't highlighted and is unable to click.. and it's becuz i have Vista..

Well My computer doesn't boot up CD for some reason (yes i know.. go into BIOS blah blah blah done that) and i used the boot setup disks from microsoft "http://www.microsoft.com/downloads/deta... but it always just seems to bluescreen when i run the floppies..

And I;ve already tried starting new.. formated everything, and started clean.. it STILL wont be up my XP CD!!!

is there a way to install this damn thing.. cuz i hate vista!!
Update: dont worry.. it's full version!!!
4 answers 4