Windows XP shortcut key to focus a particular window

Say I've got several apps open and I want to keyboard shortcut to focus, or bring to the front, a particular window. Of course I know about alt+tab to cycle through windows, but it would be great to choose a specific window with a keyboard short cut.

Answer

Autohotkey!

WinActivate, [Full Window Title]

If the window title changes, you can either use the bundled Window Spy to grab the ID, or

SetTitleMatchMode, 2

to be able to match a window with only a partial title. (There's also a regex mode, if you're comfortable with it).

The maximising would be WinMaximise rather than activate. This does not focus it, though, so you'd need to use both to maximise and focus a window.

EDIT:

Ok, real world example time.

#\::
   SetTitleMatchMode, 2
   WinActivate, is currently
return

That fire on winkey and \ (# being winkey), then focuses any window with "is currently" in the title. In this case, "User is currently status", for my IM windows.