if you're going AMD, try the nForce2 motherboards, as they are probably the best deal for gamers.
You can get pretty much any Socket A mobo for under $150, but for the best audio and performance, get an nForce with the MCP-T integrated audio. It rivals the Sound Blaster Audigy 2 in sound quality and performance.
And yes, a 2600+ will do you quite nicely for most games.
If you have any problems with it's speed, though, you can always OC