Why are you so dead set on going with AMD? Havoc may not have sounded very nice, but that doesn't mean he was wrong, because at this point intels processors are the better options, unless your looking at AMD's future processors, which wont even be fully supported by socket AM2. And im pretty sure most people on this forum are going to agree with that, save the few AMD fanboys we have hanging around here.
Your right on with vista, no reason to go with it yet unless you need DX10 or something, which you don't. I suggest the 8800 definately for the small price diference between it and the 7950, unless you wanna go for the silent edition that XFX has. As far as the RAM, those G skills are what i have, and they look sick, and out perform almost all other ddrII 800 Ram, so i would really suggest those. Otherwise looks like a solid build, good luck with it.