Welcome to the forum. Yes, you've got a good start there. One note, you are going to want DDR3 for that AM3 motherboard. Here's a build that totals $590, it's using some different components but it's still based on an AM3 Athlon II.
Good build by jbaker as always, i put this alternate build together that comes close to the $600 budget (makes it if you include rebates...i hate rebates)and includes the windows7 64 OS. I went very cheap on the case and substituted a HD4850 for the 5750. Some good combo deals.
Have gotten my hands dirty which such a build - nothing but smiles from clients when they see price/performance and do drop by Extremesystems forums for the feel of current AM3/785 Biostar chipset ^^ OCZ i wouldn't go with the Gold/Obsidian series RAM but AMD Black series good to go