If you already have a PS3 and 360, you really don't need another console as you have plenty to keep you busy at home (even if there may be one or two games worth playing).
As long as you have the intention of actually playing the PSP on the go and not just while laying on your bed, I'd pick up one of those over another console. I think the PSP1000-3000 is ass-ugly and I'd never be seen in public with one, but the Go is a sexy modern little piece of tech and since you don't have an existing catalogue of UMD's to worry about I'd opt for one of those (if you can afford it).

It's all about the game.







