Your comments

Oh ok. :) DisabledHotkeys did the trick. I set it eventually to 0x25|ctrl+alt (101) and 0x26|ctrl+alt (102). Thank you so much! This rocks totally. No need to use Alt-Tab when you can directly switch between apps from the taskbar!

I disabled hotkeys globally (NoWinKeys in HKLM policies and restarted Explorer.exe) but Win+Q/Win+W does nothing on my Windows 7 x64 with 7+TT 4.2.5. Also, on Windows 8, NoWinKeys doesn't disable the new hotkeys introduces for Metro e.g. Win+C, Win+I etc.