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

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