I saw that heading and thought you was a-spamming.
If you want to go ahead and set up a site then there's bugger all to stop you.
Bear in mind the start up costs and the amount of time you'll have to devote to running it though.
Many folks have these great ideas and then balk at the thought once they do a little more research into the actualities of it.
There are plenty of respected long established sites out there for the Xbox and so you'd be competing (for members/viewers) in a market which has some pretty strong players.
Just don't set something up and then go round spamming other forums for members though.
That's a sure fire way to get shot down in flames.