mmitch,
I'm awfully confused....
Are you NOW saying that you have a Windows 7 DVD and a legal license. But the problem is that you laptop doesn't have a DVD drive ?
In which case, just stick the DVD into something that does and create an ISO image that you can then push onto a USB stick, external drive or whatever you have hanging around.
WinXP and turn off networking, assuming the software will work with WInXP. Just don't be tempted to use it on-line.
Indeed, if you absolutely must use XP, you must plan to never, ever use that machine online !