I think your system is good enough that you are going to have to spend a bit more than $500 to get a big improvement. I would upgrade speakers if it were me. Athena, which is a brand of the parent of Energy Speakers, has last year's models on sale at
www.audioadvisor.com for good prices. You could pick up a pair of B2s for $150 or B1s for $100, and a C1 for $100, to replace the front 3 speakers from the Take5 package. That will give you a little more midrange performance. You then have the extra speakers to use elsewhere - perhaps down the road you could upgrade to a 6.1 or 7.1 receiver and use those speakers to fill in your surrounds.
You can get a decent universal remote for about $100. The URC-200 is $92
here. It's easy to program and easy to use. The 100, with a smaller display is just $62 from them!