Is COM1 the port you normally use to upload to the Duemilanove?
Before you upload the code, look in the IDE menu Tools | Serial Port and see which ports are available/visible.
One thing that might have happened is you shorted something out on the board which might have blown something critical on the board, in which case it's toast.
But a short can also trigger the USB fuse which then disables the COM port in Windows (although it may depend on your windows version - I know WIN 7 will do this). If that's the case you have to unplug the port, and if it's on a hub unplug that too. Then plug it back in again.
Pete