I've been moving development from an old XP box to a faster box that has Vista64. I had some trouble getting WinARM to work, apparently because of an incompatibility in MSYS. I found a patched MSYS dll over at http://www.madwizard.org/electronics/articles/winavrvista which solved the problem. I thought I'd post this here in case anyone needs it. Thanks to all for WinARM / WinAVR development.