CPU: AMD phenom ii x4 965 3.4ghz
RAM: 2x2gb 1333mhz gskill
GPU: Sapphire Radeon HD 6850 1gb
HD: 500gb caviar black WD
According to this benchmark
by Toms Hardware, that card runs SC2 at 1920x1080 on Ultra with 8x AF and 0 AA @ 38.7 FPS on average with a minimum of 23 FPS. If your processor at 3.4Ghz is on par with the 920 2.67Ghz that they used for that benchmark then I would say you should be all set. Hope this helps!