Will this computer run Sc2 and how many fps?

Nvidia 8200 chipset : ASUS M3N78-EMH HDMI

AMD Phenom II X2 550

4 gb's of ddr2 ram at 800 mhz.

Nvidia GTX 460 1 gb

I plan to run it at 1920x1080.

 

That will be fine. Fans is all up to you really. You can run 1 fan and it'll be fine. My nephew got an old case with core 2 duo. 2.5 rams radeon 4800 series video card 512 mb and one small fan and his handle fine without no lag with setting all ultra beside texture is high since 512 mb video card. Yours will run in all ultra. Starcraft graphics is not very video card demanding as other games. Of course one or two more fans wouldn't hurt cooling down your system. I run 5 fans, 7 fans total if you include video card and CPU fan. My system stay very cool even after long hours of playing. A case that has good air flow doesn't hurt either.