Help with a raspberry pi game system

Looking to make a low cost system for playing old games using the raspberry pi. So my issue is I don't know what OS i can use and have it still work with my emulators. And here is the "kit" im getting http://www.microcenter.com/product/423294/Raspberry_Pi_Model_B_Programmers_Kit. Also will the 256mb version be enough or would it be best to get the 512 mb model.

 So thoughts, comments, witty one liners?

bump?

http://chameleon.enging.com/

I would go with the model B if I were you, you probably don't need the extra RAM, but it's only $10 more then the model A, it has more IO, and an extra 256mb of RAM can make a world of difference.