Thanks for all your help - some good insights.
I'm very leery about buying a new motherboard - at some point, I plan on building a much higher powered computer that will probably use an i7 or its replacement chip, and would hate to spend $300 now that I could easily put towards this.
But, I graduate in a few years, and if games should probably stay playable with lower settings, I'll probably be able to hold out on this computer until I can free up more funds.