i7 2600k and GTX 570 or SSDs?

I have an SSD for FSX and other games. OS on HDD. The logic is that with Win 7 x64 and 8GB of RAM there will hardly be any paging done, so the HDD is fast enough to load the occasional program (pretty small compared to FSX). FSX, however, takes far longer to load to the initial screen and then again to load the airport once you enter the game. The SSD helps a lot here and with the amount of tinkering you are likely to do with a new system -- restarting a lot -- this will save you a lot of time. There will also be better performance loading textures and scenery as you fly and switch camera views. A faster HDD or SSD is not likely to reduce stutters, because these are introduced by shoddy programming of the AI planes and other vehicles.