I'll be the first to admit they ain't perfect, but after running both, I ain't going back to a PC. The few extra bucks for a Mac is money well spent, and for the kinds of tasks you're looking to do, it's simply a better mousetrap.
I run the XPS 400. It's several years old now but does everything I ask. Momma has a shit ton of pics on the bastard and we haven't had a single issue. Dell's site gives you options on building one. Adding on is easy.