5870 in comparison to the 5850 is a waste of cash, with the right bios(maybe not even a bios flash these days, not really kept up on software updates which might be able to do it without the flash) you can basically get the 5870 speed when overclocked, the only thing you lack is a few shaders but with the same clockspeeds on both cards in almost every game they perform all but identically.
The 5770 I've not used personally and have seen varying reports, while its high/average framerate seems to be very competitive compared to a 5850/70, its lows are reported to be a bit lower and more prone to larger drops which would be more noticeable.
Pray retailers stop ripping everyone off and return the pricing to launch pricing(as it should have been the whole way even without much stock) and then pick up a 5850.
Fermi's release is unlikely to push AMD's pricing down, the cores simply cost more to make, the pcb's more expensive and we simply won't see a 5850 at sub £150 just because Fermi is out. Likewise its very unlikely Fermi will be able to beat AMD on a price performance at any level, so you'll likely get better performance from 2x £200 AMD cards than a single £400 Nvidia card, though depending on yields and their want to undercut AMD you might see some slower Fermi cut down parts at decent prices. But considering Nvidia's higher base cost per core, all they'll do is match AMD on price/performance, not beat them as its not in their interest to give us free extra performance. personally I wouldn't wait just to get something of an equal price/performance when you can get it now.
The key question is of course though, are any games struggling on your sli setup right now? If not, wait till they do and buy then, maybe no game will really push you to the breaking point before Fermi is out anyway and you can make a better choice.
