If you want to know which assemblies are loaded in a certain process you
can just get the Modules from the Process by getting a handle of the process
itself.

System.Diagnostics.Process[] Processes =  System.Diagnostics.Process.GetProcesses();
System.Diagnostics.Process aspnetProcess = null;
foreach(System.Diagnostics.Process process in Processes )
{
    if(process.ProcessName.Equals("aspnet_wp"))
    {
        aspnetProcess = process;
        break;
    }
}
foreach(System.Diagnostics.ProcessModule module in aspnetProcess.Modules )
{
         System.Diagnostics.Debug.WriteLine(module.FileName);
}

After that you have the path, so you can do whatever you want with them.
If you dont want to load them into the current appdomain you will have to
use AssemblyName.GetAssemblyName(...). But if it fails, it is not a .NET
assembly. There are more elegant ways of doing that but i am not sure what
you are working on.

Erick Sgarbi