I was using my new Arduino on a machine that was already using some of the FTDI serial adapters. My next available port was COM12. When I tried to upload to the board I got a message saying that avr-dude could not find the file specified.
One of my co workers told me that we have run into this problem before. Any COM ports above 9 need to be accessed by \.\COMxx.
I pushed my serial port up to COM2 and it worked just fine.
I don't know too much more about this issue and whether it needs to be fixed in the IDE or avr-dude but I thought I would point it out.
Some links on the issue:
And thanks to ladyada for getting my new Arduino to me lighting quick, I'm having a great time with it.