Using dual monitors is one way to tackle this problem.

If you happen to be running on a terminal server machine there's an even better way to do this. Create a terminal server session to your own machine and start the exe in the terminal server window. Start the debugger on the console window and attach it to the exe in the other session. This is helpful if you're debugging paint or focus issues because then the debugger won't steal focus from your app when a breakpoint gets hit.

Shawn Burke, Microsoft