Since you are posting on this forum I'm going to assume you want some kind of audiophile type product rather than junk.

Therefore, I'd recommend getting better speakers and maybe not going 5.1 all at once.

The Epos ELS-3 speakers are under $350/pair. So you could get three pair of them for a bit over $1k. One pair would be used as the center channel.

Then you would only need a subwoofer. Or, get two pair and a sub and do without the center channel for a bit. You'd still get that information out of the front speakers.

The Hsu STF-1 Subwoofer is $299 here:

http://www.audioholics.com/productreviews/loudspeakers/HSUResearchSTF1p1.php

So, as a 4.1 system you'd be paying about $1k.

I honestly don't think you'll get the sound you want from the Overstock system.