Well... in my opinion u should boy xxxbox, thats a REAL gaming console. Ps vita is just little playtoy, but u can take it everywhere... but if you put little bit more money for this, you can buy ps3. I would :p
I have the vita and right now I barely ever use it. I wouldn't get an xbox though I'd either wait until the Vita gets a bigger game library or I'd but a PS3.
Why are people comparing Xbox to Vita, One is Last Generation Gaming (Xbox 360) One is Next-Gen/Current Gen(PS Vita)
But more to the point the vita is a great great handheld console but if you aint going to play it all the time, they are a waste of £200 or what ever price and Currency you are in!
The games are OK for now, will get better as the console is out longer, and they can use the Vita to its full power!