I'm sure I remember trying to find out the info on your speakers when you joined. If I recall your setup correctly, I'm thinking there might be a better way for you to really get started. Check out this deal.
http://www.av123.com/products_product.php?section=speakers&product=109.1 Four x-ls and an x-cs for speakers, an x-sub, Denon receiver and DVD player for $999. It's entry level to be sure, but it would be a far greater upgrade as a package than trying to work around the limitations of your current speakers. Plus, it is a solid foundation upon which you could build a great system over time, even starting by adding better mains and turning good 5.1 into great 7.1 later.
It's just a suggestion I'm throwing out there. I thought it looked like a heck of a deal.
Note to Seth: With great power comes great responsibility, mighty Ninja.