Should be fine, make sure you have disabled AA in the graphic driver settings.

its a gt440, *almost* (i could faintly recall lower models, though i wouldnt be too certain since they dont interest me one bit) the lowest end of the nvidia 4 series, not a miracle machine

anddddddd you have an amd proc. proc plays quite an important role in sc2, unlike majority of games that only require a strong graphic card (well, actually if you've been playing modern RTSs like shogun2 or sup com, ALL of them requires a balanced out PC which also means, a decent processor, ample amounts of RAM and hdd space, and of course the graphics card)

your processor not fast enough . sc2 utilize more processor than gpu.

go here to check wether your hardware is strong enough to run sc2 and other games http://www.systemrequirementslab.com/cyri/