How to format windows 7 ultimate without removing the windows itself?

[SaulVT]

I just bought a new sunlife Microsoft Office 2007 Professional Plus Serial Key tomorrow and need my laptop to run Windows 7 Enterprise Product Key for their software. Currently i have Office Standard 2010 X64 installed. I want to know if I can split my hard drive and when computer boots I can choose xp or Office Home And Business 2010 Key. So I can use xp for work and windows 7 for home. Since i don't have the cd for Windows 7 X86 I don't want to remove it completely. Any suggestions and help would be appreciated!