gtx 550 is faster, but paired with the i3 I'm not sure. Usually when people use the i3 in a gaming computer they get faster graphics card like the gtx 560 ti or the radeon 6950. Those are both in the $200-$230 range. However the intel 4000 should be able to run skyrim and most MMOs. My friend has a macbook pro with a second gen i5(2-core since its portable and only 2.3ghz per core). With paired with the intel 3000 is able to play Skyrim once it's ported to run on the mac. Any Ivy-Bridge processor you can find will have at least twice as many cores, a higher clock speed, and the hd 4000 instead of 3000. So if Skyrim and MMOs are all you are going to play then go with the ivy-bridge. If you wanted to play other games in the future like Battlefield 3 and stuff you should go with the i3 and any of the graphics cards I mentioned, but I would stay away from the 550.
http://www.tomshardware.com/reviews/ivy-bridge-benchmar... Skyrim benchmarks with hd 4000. It's about the performance of the 520 which is about 1/4th of the 550ti performance. It is playable on the hd 4000 as you can see. I would recommend an i5 and later buy a discreet card. No point in upgrading to haswell, one generation difference is never worth it. If you need a new rig now buy it now, if you don't, then wait.