why not try and grab the The 7870 XT cards the knock off 256 bit Tahiti GPUs
$239 a pop http://www.directron.com/ax78702g2dhp3e.html
Get Far Cry 3 free x2 sell them off for like $30 a pop and you end up paying $420-$440 for the two cards if you get $250 for your 5970 that drops you under $200
Newegg its a Rebate but same $239
PowerColor PCS+ AX7870 2GBD5-2DHPPV3E Radeon HD 78...
7870 XT Tahiti Le gives 97% of the 7950s performance but costs $60 less per card
what to expect its cheaper than the 7950 and 3% slower the Tahiti LE route is also cheaper than NVIDIA's 660Ti sli option. but SLI seems to scale a bit better as of late.