I agree in getting a core i7 system ideally, but I can understand that this is a much cheaper alternative and I think you are getting a pretty good deal on the system at that price.

For SSDs, SATA2 is fine, some of the newer ones will hit the max transfer speed fairly quickly but this is for large sequential reads. The value of SSDs for us is in small file random reads which normally run at a slower transfer rate and high IOPs which are not so limited by the SATA2 bus.

For the price of the system I don't see any harm in trying it. Get the system, add your GPUs and an SSD. I use 2 x intel X25M 80gb drive in raid 0 which work well. If I was buying now however I would get an OCZ vertex 2 drive which uses a sandforce controller. If you are looking to buy in the new year then there will be a new generation of SSDs available but keep in mind these will be more likely to hit your SATA2 bus limits.

Windows 7 should be fine with the dual CPU setup. Isboxer will see 8 cores for current i7 chips with hyperthreading enabled so I can't see it having a problem with a dual CPU setup although Lax should be able to confirm this.

If you get the system and it doesn't perform to expectation then all you have lost is 30 bucks. You can buy yourself a chiny new i7 system and put the dual 460s and SSD into the new build without a problem. On the surface however I can not see that system having any problems 5 boxing. Saying that however, you could always just upgrade your current system with dual GPUs , another 4GB ram and an SSD and I think you would probably get similar performance. Your current system is probably limited by the ram mainly so if you wanted to see if this would be worthwhile, start with the ram upgrade and work from there.

Cheers