|There are a number or ways to do that. Personally I'd use a virtual machine instead of a dual boot.|
One way is to change boot order in bios. Set the second drive to boot first. On newer systems the ubuntu would then install to the second disk and not affect the first disk.
I do that usually.
Another way is to leave bios the way it is and use the installer. Then your xp boot loader would be replaced by grub, hopefully it will work.
Another way is to use wubi to install and maybe later un-install ubuntu.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.