uninstall window server 2003

I installed an evaluation copy of server 2003 to practise for the course im currently doing, unfornately i deleted Xp in the process..
I now want to re-install XP as i need dual boot ( XP and server).I cant seem to do it, when i run my XP CD, the installation bit is greyed-out. I ve tried to uninstall server 2003 , but it is not allowed me either

Anyone know a way around this problem.
Desperately need some help….cheers