The Windows version of iTunes is indisputably the poor cousin compared to the Mac release. One feature it implements patchily is support for the multimedia keys found on many PC keyboards, but you may be able to fix that with the mmKeys.dll plug-in.
If you've installed suitable drivers, iTunes will recognise keys for play and track skipping, but many users find that they don't work if iTunes doesn't already have focus. The Everything iTunes blog runs down how to install the mmKeys.dll plug-in to stop that happening. One key point: iTunes needs to be restarted to make the fix work.
It's not a perfect solution, but for owners of flashy keyboards, it's definitely useful. Now, if only Apple would give up on trying to shove Safari down my throat with iTunes (yes, there's a hack for that, but it's one you need to reset every so often) . . . Thanks Benjamin!
mmKeys.dll – Use a multimedia keyboard with iTunes [Everything iTunes]