Buy it. I bought the Onkyo HT-S770 in July 2004 form circuit city for $405 plus tax. Consumer reports rated it as their #3 HTIB. I found the receiver extremely easy to navigate through when setting it up whether by remote or the receiver face. The sub does very well when placed near a corner. Flimsy metal poles won't hold these surround speakers, unlike small satellites speakers. The remote isn't backlit, an acceptable sacrifice at this price point. Not sure if this will replace your existing set up or be an addition to. Strongly recommend to purchase 12 gauge speaker cable to replace the twisty-for-your-bread cable they include. Also, look into a good sub cable if you don't already have one. I know you're on a budget, so wait until circuit city puts it on sale again for $400. Sometimes you can get a better price if you buy it from circuit city online than inside the store. The price on this HTIB seems to change every 2 weeks or so. With the $$ you save, visit Blue Jeans cable online for 12 gauge speaker cable (product 5000UE) ;only 40 cents a foot!
http://bluejeanscable.com/store/speaker/index.htm
For a sub cable, visit Impact Acoustics for a Sonicwave sub cable
http://www.impactacoustics.com/product_list.asp?cat_id=804
A friend of mine purchased the HT-S780 for his house and loves it. The 770/780 systems are great systems for the money. I like that the 780 can utilize an $80 docking system from Onkyo to integrate an ipod.
If you buy it online and pick it up at the store like I did, prepare to handle a box the size of a small refridgerator. Happy listening!