I'm having trouble finding information on GetAsyncKeyState - can anyone point me in the right direction? A couple of links would be welcome.
(thanks ooble)

http://msdn.microsoft.com probably has all your future answer to questions like that, just for reference. You can even download a copy of MSDN in the form of three CD ISOs if I recall correctly from their website. (You used to have to have an MSDN subscription for the software).

well as a quik veiw ...

the API you talked about checks when you pressed a keyboard character
this API is helpfull to create key loggers or check for hot keys such as

<ctrl>+<alt>+<delete>

for more info check the MSDN library and get source codes from this website i guess i don't remember :

www.white-scorpion.nl