Can't burn CDs or DVDs, can't run for more than two hours without a crash.... Have you noticed how Vista will delete your MP3s if it thinks you downloaded them illegally? (it won't ask you, it just deletes them from your computer)
* The new VirtualBox can seemlessly integrate Windows apps on the Linux desktop, much like OSX's Parallels. I.e, you don't see the Windows desktop at all. You see the Windows app on your Linux desktop like any Linux app would.