kraada wrote:I'd also like to point out that while I do have sympathies towards all Linux users (as I was one myself for over a decade)....
Gone back to the dark side huh? Come the revolution this shall... never mind.

Anyway, back to OP's position. To the best of my knowledge Wine provides a link between Windows APIs and Linux based on a set of parameters designed for each Windows configuration the user selects... XP, Win7 etc. It does not create a complete Windows environment per se, thus some of the things PT4 and/or the poker clients do may not get trapped/interpreted. Virtualbox (and VMWare) create a space (with APIs) into which a full Windows installation is inserted. It is the same Windows environment in a virtual space as you would create in native space and hence the reason why I believe there are fewer problems running PT4 under VB than under Wine.
In my own case, I have been running PT3, PT4, Win XP, Win 7 and the poker clients in VB under Linux for about 3 years.
The real difference between Wine and VB is that in VB you need a full Windows licence.