loading windows XP on a laptop loaded with vista

I got a laptop loaded with windows vista. The problem is vista is not supporting many softwares (like winrunner, load runner etc. Even some one told me that it doesnot support oracle even though i didnot test it.)

So I want to partition my HD so that I can load windows XP on one partition by which I can run any software till vista becomes fully functional.

Suggestion please.