Replace "alt+f4" with "win+w"

...or choose anything else, "win+q" is quite popular as well.

1. Get Autohotkey
2. win+r, enter: %AppData%\Microsoft\Windows\Start Menu\Programs\Startup
3. create "win+w.ahk"
4. paste this in there:

#w::Send !{F4}
return

if you are interested in more, here's a quick symbol rundown:

# = windows key
^ = ctrl key
! = alt
+ = shift
<^>! = alt gr

or go read the whole thing

now enjoy not crippiling your hand every time you want to close a window