Comment about my gaming configuration

Your motherboard selection is not going to work with that CPU. In order to gain support for the 9xxx series of CPU you need to select a 780i motherboard or better if you go with a NVidia chipset. When it comes to overclocking, every system is different. Expect it to be better than stock, try not to form any expectations of numbers, it will avoid any feeling of disappointment if your particular CPU can't be clocked as high as someone else's. 3.0GHz is probably a safe bet, however, which means you'll be past the point where there is any impact on performance other than time demos.

Tom's Hardware had a complete article on RAID vs Raptor a few months back. Personally, I don't believe you will see much, if any advantage to the RAID setup while gaming, and only a stopwatch is going to notice the difference of 1 second in startup times. IMO, it's better to have an OS HDD, and a second HDD for your apps and data.

Unless you are gaming at extremely high resolutions, I would just go with the 9800GTX over an SLI pair of 9600's.

Sound card:You would see a very slight increase in performance, and would gain access to additional sound content in some games.

The round cables won't affect cable routing. I'd just save the $$$.

Overclocks: I would select CPU and memory. This will ensure both are tuned to each other for maximum performance. I'm not a big fan of GPU overclocking, it has more effect on benchmarks than actual in game performance.

Vista doesn't need the level of tuning to be useful that XP did. Just disable the UAC when you get the system, and you'll be good to go.

uac = user account control