I am looking to upgrade my 3.1 system to a 5.1 system (finally). I have 2x Polk R50s, Polk CS1, an eD A2-300, and an Onkyo 705.

I have seen some people say just go ahead and get 4x Polk R50s. But I have read several articles about it being ideal to have the surround speakers 2 ft or so above head level. So how much surround effect is lost by having the floorstanders? I am speaking in terms of HT, not music.

On a side note, I am completely open to other suggestions for surround speakers ($200 or less for a pair).

The R50's would make very nice surround speakers. Or consider getting 2 Polk Monitor 50's for the fronts and use your current R50's for surrounds. Great sale prices on cherry or black veneer M50's from amazon.com (with included shipping) or frys.com (shipping extra)

I will definitely look into it. Do you think that the Polk Monitor 50s make better fronts than R50s?

And does anyone know how much effect is had on the surround sound by having floorstanding speakers?

But I have read several articles about it being ideal to have the surround speakers 2 ft or so above head level.

If you read what THX, DOLBY or DTS suggests, the ~2 ft above ear level is for side surrounds NOT rear surrounds. Rear surrounds should be at ear level.

Floor standing speakers will be just fine for surrounds. They can cost the same or less than monitor speakers when nice stands are factored into the equation. Sitting a monitor speaker on a crappy stand doesn't work very well, so in many cases, a floor stander actually works out better. Not everyone wants to shell out ~$350 for a pair of Atlantis Reference Stands like I did for my surrounds.

http://www.audioplusservices.com/atlantis/reference2.html

But, with a Chocolate Lab that has a tail that when it wags, can be a lethal weapon, I needed something rock solid that he wouldn't knock over if he got excited. The fact that they improved the sound tremendously, was icing on the cake.

Good luck either way you go....

as for the Polk M50's, I have not heard them personally...but Polk has a good reputation for incrementally improving their speakers as you go "up" in their speaker lines. They are discontinuing the Monitor series, so the pricing is really great at the current moment.