That graphics card and monitor could use an upgrade, maybe the SSD too (that's actually what I have - definitely the best choice at the time). CPU is nice though! You won't see much benefit at all from what's out now. For monitor, the Dell U2412 or U2312 are brilliant displays and very competitively-priced for the quality. For graphics, the GTX660 offers amazing performance for the money. If you're feeling spendy, GTX670 is even better, but really not worth spending more than that - it's pretty much as good as a single GPU gets.
That's a good point - I'm in the same situation so should have thought of that :-) There actually were X58 boards with SATA3, it just wasn't integrated in the chipset and seems neither of us thought to buy one with it added in! You won't get much better than the X25-M on SATA2 so stick with it I guess. 7850 is OK, but it's barely any cheaper than the GTX660, provided you're looking at the 2GB model (and you really should be). Same monitors - most important thing for image quality to skip all the TN-panel displays (so the majority of them). You want an IPS-panel display, and the Dell U2312 is one of the absolute best examples for reasonable money. Aria have the U2412 (so 24" version) at £180 at the moment. I think the 23" can be had £40 cheaper.