This is kind of advanced, but it's what I do an I love it.
Go to
http://www.vmware.com and download the VMWare Workstation program, then create a Win98 SE or DOS (or whatever you have) virtual machine on your XP machine. Install your games on there and play away. I play all my old DOS games on a 98 VMWare machine. May lag slightly, but nothing major.
A free-ware, opensource option to VMWare (but is more difficult to get going properly) is:
http://bochs.sourceforge.net/
Good luck.