That end task thing is totally Vista's weirdness. VC:MP exits the game using ExitProcess() WinAPI call, which should instantly close the process. If it doesn't, it's Vista's bug.
Vista has a different, rewritten kernel, probably with less optimized code, and does not introduce very useful new features except the graphical design and "eat-up-all-resources" feature. The only thing that is new and good in Vista is the built-in IPv6 support.