When I clicked on your links, I could not find any indication of the impedance of the speakers you are thinking about buying. Do not buy them if you don't know what their impedance is, as it may be no better than what you already have.
Also, judging from their claim that a cheap two way with a 6 1/2" woofer goes down to 20 Hz, I wouldn't trust anything they say.
At the price range you are considering, I would try to find something used on Craig's List.
Or, if you want to buy new, you could get some Polk speakers pretty cheap, too:
http://www.bestbuy.com/site/olspage.jsp?skuId=8828012&type=product&id=1207956903491
You might even be able to find a better price on them; I simply selected a site that I happened to know sells Polk speakers. Also, you may be able to go and look at them and listen to them before you buy, which is always good with speakers.