Actually the backwards compatibility was the cause of games screwing up on my Vista.
So here are some REAL tips.
1. Do not install games in the default C:\Program Files\* folder, as Vista is protecting this folder from writing, which can cause games to freeze.
2. When the game is overwriting files to start (SA:MP, MTA:VC, MTA:SA) let it run with Administrator rights (ask your parents if needed).
3. When after installation there is a prompt to reinstall with more rights, DO IT, even if the initial installation seemed to be ok.
The games of Watti all run on my Vista from standard installation, without having to set any options.