Checking for RealPlayer

I need to see if the end user has RealPlayer installed (for playing some videos, otherwise I'd point them to Winamp). I'm not going to be too worried about which version, since RealPlayer should speak up if it needs updating.

My question is this: does anyone know of the best way to check to make sure RealPlayer is installed?

I figure I can do it by checking if there is a registry key defined at LOCAL_MACHINE\Software\RealNetworks\RealPlayer. This sounds good, and works on the machines I've tested it on, but I was hoping someone could tell me if this solution was robust.