Just with regard to the question on 32 bit colour depth, russnjan, the following list may help clarify things:
1 bit = 2 colours (monochrome - black / white)
4 bit = 16 colours (ah, Windows 3.1 how we loved you - or not!)
8 bit = 256 colours (really bumping things up a notch when that became the standard for an OS)
16 bit = 65536 colours (making things look almost realistic with the range of shading you could finally have)
24 bit = 16.7 million colours, also known as Truecolor.
After that things start to get a bit silly, with 32 bit being potentially 4.2 billion colours, but it's generally 24 bit with an extra 8 bits of non-colour data such as alpha or bump data.
Windows 7 may support up to 48 bit colour (at least that was promised a couple of years ago, not sure if it was delivered), but as this would be 281 trillion colours, who would know? Exactly how good is your monitor? How good are your eyes? Could you tell the difference between 24 bit colour and 48 bit colour?
Anyway. As you see, the colour depth has nothing to do with the programming of the OS except in as far as that OS will support graphics capabilities generally. To have a 64 bit OS is not to require a 64 bit colour depth.
