If you're gonna Overclock at all - and to be blunt, NOT overclocking a winchest core is practically a sin - don't buy a 3500+. The 3200+ and the 3000+ pretty much all reach the same overclock of around 2.5-2.6 Ghz on air. I've got mine up to 2.5Ghz (250x10) by loosening up the ram timings to 2.5-3-3-8. Many on the net think they're all essentially 3500+ (same fab, sab silicon, same design) and AMD could sell them all as 3500+ if they've got the demand.
Mobo is fine. MSI makes pretty fine A64 board. The Neo2 plat I'm running is a nice piece of machinery.
2 GB of Ram will quite possibly hurt performance. The on-board Memory controllers of the AMD64s generally don't like using more then 2 dimms, and it will automatically apply a divider if you've got that much ram. Some of the later winnie's can handle 4 dimms at DDR400, but it's far from guaranteed. Unless you're planning on doing something -really- memory intensive, I wouldn't expect 2GBs to really improve things over 1GB.
A single 6800Gt will outperform a 2-6600gt SLI setup even in SLI enabled games, and will run circles around them in anything not SLI enabled. Given how questionable SLI is in principle and how few games it actually works on, not to mention the large budget here, I'd spend the extra $80 or so and go with a single 6800GT.
The power supply in the MGE viper has a weak 19-Amp 12 volt rail. Running SLI on that would be a real, real bad idea. Even a single 6800gt is probably gonna be power starved.
Make DAMNED SURE you have a floppy if you intend to install windows XP on a SATA hard drive. You absolutely must install the SATA drivers to install windows on a SATA and drive, and microsoft, in their infinite wisdom, chose to only let you install them from a floppy disk. It don't care if you've got a cd with em on it, or even an IDE HD with em, you've got to have a floppy drive.
