If you're someone on the go and out a lot then you should go with the smartphone if you don't have one already. If your a hardcore gamer that is going to be online a lot go with xbox. Lastly if u need a laptop go with that but I would hold out on the laptop till back to school shopping starts they usually have way better sales for better laptops.
So basically I would go in this order...
1. Cell Phone (comes with internet so u don't "need" a laptop)
2. Xbox Live (living with ought live won't kill you go through campaign mode a few more times)
3. Laptop (hold out for a 6 gig that in my opinion is the best amount of ram to have)