One thing that bugs me about putty is its cramped GUI, which isn't even resizeable. (The terminal screen is, but not the windows in which you configure the connection parameters).

Check out Xshell 4. It's a perfectly adequate PuTTY alternative with tabbing and fully re-sizeable windows.

Ah, gotcha. Yes, this is a huge gripe of mine as well. I don't want to have to launch RDC just so that I can then launch a cmd.exe instance and pscp something to a remote machine.