Windows 7: Mmcss ?

Multimedia Class Scheduler Service (Windows)

Gaming Online, mmorpg.
Can I get any benefit from making things a higher priority in the games folder?
Not the audio tweak.
This is about thread priority.
Does setting an app to run at an "above normal level" priority do anything different from above?
If yes to these questions, does doing edits, to the games folder, affect all installed games on the system or do I need to do things on an individule basis?

thanx