How to re-map the command-tab hotkey?

Since I have to use Windows occasionally, and Windows is so dumb that it allows nearly non customizations of system hotkeys, it leaves no choice but to modify the hotkeys of Mac OS X, although obviously Mac-like hotkey scheme is much better than the Win-like one. Anyway, I tried add global customized hotkeys (like copy->option-c, etc), but there are too many to modify. So I guess a more convenient way is to swap command & option keys. I've tried it for some days and it is handy, unless one thing: one of the most important keys, the command-tab, cannot be re-mapped. This is very annoying because as a programmer I use this hotkey quite often. Is there anyway to re-map this hotkey to option-tab, or any ideas that can help me solve my problem? Thanks in advance!