Im mainly looking for advice on the processor and motherboard. The motherboard has to be SLi compatible for future upgrades. The mobo and cpu are fine, however, if you are thinking of overclocking (now, or in the future) then take a look at the dfi lanparty range of mobos. Buy a seperate hsf for the cpu (if you can buy the cpu as oem) Artic cooling freezer 64 pro (about £17-18) are best, and will cool the cpu to well below the stock hsf, will also be quieter.
Whether it would be worth looking at AMD2 so i could have DDR2. I know that the RAM is faster but will it be noticable? At the mo am2 is actually slower than x64 cpus.
Also would it be worth looking into a hard drive that runs at 10,000rpm instead of 7200rpm? Louder and push out more heat, way too expensive considering the difference.
And most importantly how will it fair at games? will it survive for a couple of years at a high quality, or will it be drop quite quickly? i know technology moves so fast its hard to stay at the top. It'll be great for gaming, as for how long it will remain this way, can't really answer as depends on a number of variables.
PSU upgrading can't get better than Seasonic range.
Hope this helps.