Hey Bob, just upgrade your RealPlayer with the necessary codecs is all. Go to the RealPlayer web page and find the missing codec(s), download and then install.
Although it's on my pc I don't use RealPlayer pedominately for several years now since that bug/virus/trojan/worm whatever scare hit the web. Not sure if it was true or not but I use either Windows Media Player for video or WinAmp for audio...my RealPlayer is a minimal installation...just the basics is what I mean and use it only when there is no other choice.