Re: which system is better?
You can use all online features like playing online shooter (like CoD4) or any online Game. You can access the Internet via the Internetbrowser and the Playstation Shop where u can buy stuff and download free videos and trailers. All that for free.
Later there will be online games where u have to pay monthly , but thats normal (MMO Games r mostly pay2play).
To go online with XBOX u need to pay the XBOX Live Service. I dont know the rates, but after u paid that, you have the same options like PS3 does. But I do not have a XBOX and dont know so much abt it.