How to assign alt + f1 key to an opened Windows application

Question

I usually have more then 10 opened application windows. When I write code I need to switch fast between a browser, an IDE and terminal windows. Alt + tab is too slow, too many windows to choose from.

Virtual desktop is a work around for me. On a first desktop I keep browser, on a second IDE, etc. So I am able to switch fast between my most important applications.

And the question. Is there an utility for Windows XP / Vista which allows to assign a keyboard shortcut like alt + f1 .. f10 to an opened application window?

UPDATE: All programs I've found allow to define a shortcut to an application. E.g. they will open new instance of Firefox instead of switch to an opened one. Closest to what I need is Switcher. It displays big thumbnails of all open windows with assigned numbers to press.

UPDATE2: Thank you all! AutoHotkey is great. Here is a part of my test script.

SetTitleMatchMode, 2

#z::Run http://stackoverflow.com/

^!n::
IfWinExist Notepad
    WinActivate
else
    Run Notepad
return

!F1::
IfWinExist Firefox
    WinActivate
else
    Run Firefox
return

!F2::
IfWinExist Commander
    WinActivate
return

!F3::
IfWinExist Carbide
    WinActivate
return

Answer 1

Just use Win32 api KBS.

Answer 2

There's a fair number of shareware apps for keyboard shortcuts out there. Take a look at Stardock's Keyboard Launchpad, it's supposed to be able to do stuff like that.

Answer 3

Autohotkey I've found to be very powerful.