Let me give you an example..
playing basket ball without shoes...
it can be done...
if you're michael jordon, you might still be pretty good sans shoes..
HOWEVER...
AMD is the worst choice for starcraft 2.
I don't know what motherboard IBUYPOWER uses in these budget builds, but likely something cheap, which means you'll be highly limited in overclocking...
AMD overclocking is much more mother-board dependent as well because it requires NorthBridge overclocking to achieve better SC2 performance.. and this part of the OC has nothing to do with the CPU you buy..
To achieve performance parity with an Intel CPU in Starcraft 2, you need a 4.8 - 5ghz AMD cpu, on a high end Motherboard that can do significant North Bridge OC as well..
This will cost significantly more than an INTEL platform,, ONTOP of that, it still wouldn't run as fast..