Replacing Windows 2000 with Windows XP

I have a Dell Dimension L700CXE with Windows 2000.My daughter put a disc in for a game and now it barely runs.I have a newer Dell with XP and I would like to install XP into the older Dell.Can anyone walk me through the process.I’m also getting the following error coming up on the older Dell :a required .DLL,WINSPOOL.DRV was not found.I love this old computer and want to save it if at all possible.Will someone PLEASE help me.My e-mail is zepplindio@yahoo.com