if the 5870 is $400, and the $5970 is $600 and supposedly (driver issues aside) offers the performance of a 5870x2... then isnt that worth it? $600 < $400 x 2
5970 is a monster card and also matches 2x5870.So easy choice for me 5970 no comparision.
Cheaper ,single slot and fast as hell.
Others will have different opinions but for me 5970 was the wise choice.
the 5970 stock is a little slower than 5870x2... they wanted it to come in under a 300w power margin so it's clocked a little conservatively.. but you can always tweak the clocks yourself.. I think bang for the buck a 5970 is probably the best single card solution for an eyefinity setup.. if you are thinking at all about two 5870s, a 5970 would be the better choice imho... the trick is finding one in stock.. there have been a few in the FSFT section and some on ebay for way too much..