Well, there aren't exactly any more benefits as of now
, but in the future, you will probably be glad that you got that extra 512mb of ram.
Ram doesnt necessarily make the computer run "faster" if you already have enough and add even more, but it helps it to access things quicker without being bogged down by all of that memory flow, so in the future when games start requiring 1 gig of ram (and as crazy as it may sound, that is probably not very far away from happening) you will definetely be doing good in the "ram" department. :P
As of now I just have 512........but i may get more, because games are beginning to take More and More and More ram, so now is probably a good idea to start upgrading.......again......hehe