Only voted for Xbox "720" because I like how Microsoft treats hackers/modders
Rofl.
I'd suggest a laptop with some nice accessories so it can also double as a makeshift desktop.
That's what I'm doing. Also, DON'T GO CHEAP ON A MOUSE. Anything under $30 will be garbage. Anything wireless under $40 will most likely be garbage. You'll want to get a wireless if you're using it for a laptop. They do have a tiny bit more lag (I've never even noticed, but it's there) but it's worth not having the cord snag on everything around you.
How much more powerful would a desktop be vs a laptop?
The thing is, there's a point where upgrading doesn't really make much of a difference unless you have to play on the highest quality in every game, can't settle for a single bit of noticeable lag, etc. I'm not saying buying better parts is pointless, but unless you're playing nonstop or rendering huge videos each day, you're not really getting your money's worth.