Old PC & New PC: Can I Use Both?

Sandy from Sparks, Nevada writes: I have a new laptop that came loaded with Windows 7. My desktop, which I love and adore, is loaded with the original (and updates, of course) of XP. I have no plans of changing the desktop, its still working great, but the laptop is new and I'm wondering if I will have an compatibility problems between the two since they are both hooked up to the same router and wireless printer. The laptop is still in the box, not set up yet.... Answer:The good news is if your older computer is...