Russound has a really good plasma proof IR. I use them all the time and have had no trouble. One warning though, if you are using IR repeating through you house for distributed audio control or distributed video, Use only the Russound. Weve had some system nightmares combining russound with others.
If you want to try to keep using the IR system you have, you can sometimes use it with plasma if the reciever is behind the front plane of the plasma screen (but not usually). If you need a setup and can't find one PM me and I'll help.