This is a Thermaltake 650 PSU:
http://www.thermaltakeusa.com/Product.aspx?C=1264&ID=1853
As you can see here it gives you 4 parallel PCI-E, this means if you get it you can crossfire any hi-end Graphic card couse most of them they use two pci-e connectors. Else you gonna run and find 2 molex to pci-e for every extra card you add screwing the cable managment, blocking the airflow and some small power loss for every extra connection you do.
After Testing HD5770 in 950Mhz 1350Mhz it runs fine with 81 Watts and gives 75 FPS and 90 FPS needed in the most games so you don't really need the CrossFire, it gave 59 C in the games and Furmark 1.8 extrem test 1 hour raised the watts to 87 and the temprature to 69 C (+-1 day ,-2 night) with the fan in 100%, very hight noise level. The 80 C and above you will get in HD5770 CF is a reall problem Furmark 1.8 will burn you out and i suggest we wait for the 32nm GPUs, DDR with lower operating volts.
Full view 1280x 1024 in
http://admins.bnb.gr/~giatrakis/Furmark.jpg
Ati and Gigabyte they did a nice job is an exellent choise so mutch million furr hairs can't be rong.