Don't take this the wrong way, but that was a HORRIBLE decision buying a HTiB. Like yourself I gave myself a budget of around $500 to work with and originally was going to get a HTiB. Then I realized they don't do HD audio (since you have an HD tv, you want that). Then I finally said, this. It may be too late to help you, but on Boxing day they had a Pioneer 1018 receiver going for $400 (they probably sold out in a few hours), regular $600. Now this receiver is awesome, HD audio, tons of ports, etc.
The real thing is it only does 130Watt/channel. For me that is ok because I don't need to be blown back by sound. Now with that said, it is 7.1 so 7x130=880Watts. So in essence by $600 (we will say the regular price), has less Watts then a 1000Watt HTiB. However, those receivers are RUBBISH! My mother owns a HTiB and how that thing outputs 1000Watts is puzzeling, because first of all it doesn't because it would blow the thing in like 2 seconds, but the sound quality will be THE SUCK!
In short, YES, bite the bullet and buy seperate. Just make sure the receiver decodes Dolby TrueHD, and DTS HD Audio. Those are the two HD codecs, for blu-ray etc. This is basically a failsafe that your receiver will last longer than 20 days (technology wise). Just like I was telling my dad, why spend $250 on a receiver that doesn't decode HD codec's, it is just wasting money into OLD TECHNOLOGY. Because sooner or later your going to realize you should have just spent the money (like I did, and I am super glad I spent it). For speakers, I would hunt for deals like me. I don't want to blow $800 on speakers so I am just waiting it out until I find deals. Like Visions has 2 M20 Polk Fronts for $148 (regular 600!!!), and I picked those up yesterday and man they sound awesome.
But little speakers for fronts, like you get in HTiB, or other packages would confuse me. I haven't heard the package ones (like Polk 6750 package), but having these things now I couldn't go to little speakers for my fronts. These are 3 feet tall, and those little things are like 6 inches (you get stands so they are up high at ear level, but still, wtf!).
Oh, and if you already have speakers, even if they are just old ones, then just buy a receiver, and hook those up until you get more money, or decide you want better ones.
If you can, take the HTiB back, and search around for a good receiver. TRY and go to Bestbuy and see if they still have some of mine, but I assume after nearly 10 days, they are sold out.
Just please, don't buy old Technology, spend the extra money.