|A few ways are normal. |
One is to dual boot. Install two OS's on the same drive. Many web pages on ways to do that.
Second is to use a virtual machine. One can convert (or even keep) the xp install in some form that can be later used as a virtual client on the Windows 7. I tend to use P2V but have used clones and images and backups to re-create to a VM.
Why did it take me over a year to phone in a problem to ATT?