[xmonad] Moving windows to a workspace based on their title / console applications in terminal emulators

Hi all! For many purposes I am using console applications, like centerim, irssi or mutt. Now when I start xmonad, I'd like to open a bunch of applications (Can I do this via .xinitrc), like firefox, mutt, etc. These should then be moved to a workspace, based on the application running. So when I start an rxvt-Terminal with mutt, I want this to be moved to workspace 3, how can I do this? On top of that I can't figure out how to move gimp to a special workspace. I have setten it to float, but I tried the class names, gimp, Gimp, gimp-2.2 etc. but it won't go to the workspace I want, when I start it. Anyway what is this class name to identify a window? Is it the process name? Thanks in advance, Bastian Schnitzler