Determining CLR .NET Installation Directories

All:

This *should* be a simple question, but I cannot find a definitive answer on
the net so....

I have both versions 1.1 and versions 2.0 of the CLR/.NET installed on my
machine. I want to get a list of the root directories under which these
live. I can use the following statments to get the most recent info...

System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory();
System.Runtime.InteropServices.RuntimeEnvironment.GetSystemVersion();

However, how do I get a list (similar to what these methods yield) for the
v1.1 as well? In other words, is there a definitive way to iterate the .NET
installation dirs?

Thanks,
John