Neither styling widgets nor adding transparency will help you getting an existing desktop application to the tablet. It should be done with as little changes as possible, that's the whole point.

Also, neither styling widgets nor adding transparency will make for a better user experience (in general; I admit there are exceptions). Consistency is one of the most important points in user interfaces, and not using stock widgets but styling your own instead brings inconsistency. (When I say "consistency", I mean consistency not only within an application, but throughout the whole platform and, even more, across platforms. The user knows certain concepts from the desktop, and its a good thing to try to reproduce these in phones, tablets, PDAs or any other computer-like devices. Nobody wants to learn how to operate a new device from scratch.)