5.1 for $250 is hard to work with.
I had the same thing as you. I went through Klipsch Promedia 5.1 Ultra setup, several Creative and Logitech setups, and I was never satisfied with any result.
I finally broke down and purchased a used Pioneer VSX receiver from Ebay for $150 and a pair of Insignia coaxial 6.5" driver speakers from Best buy for $50 when they where cheap and I have been happy ever sense. The dynamics are off the charts compared to any "computer" package, and I enjoy them greatly. Problem is, as good as they are compared to computer speakers, they are bottom of the barrel value and entry level. I just cant accept that.
But then, I always wanted more. So I started doing a LOT of reading here and I learned loads. My interest became a complete obsession (more or less) and I constantly dream of owning so of the most sought after speakers, but I never have the budget for it. So be warned, when you open this can of worms, it wont stop!
Currently I have a set of Ascend CMT 340's L,C,R on the way, Along with a set of Rockets book shelf speakers from Ebay, Both set used and had at a great value. That's triple your budget on just the CMT's. I'm also looking at Rythmik for a sub woofer option, and I have a feeling that will be close to the $500 mark.
And I started with $200 mind you...
So if your looking for the quality, and your budget is limited, start small, with a 2.0 setup, or a 2.1 setup if you need. Its much more worth it in the long run!
I just really read your post. The upper response was pretty generic. You already have a receiver, the Swans are a good choice, but they are already powered. If it was me, I would take the $200 to eBay, and look at some infinity stuff, or If you want to follow my advice above, $200 can get you a real nice set of 2 bookshelf speakers that will be light years away from anything from the computer market.