A buddy of mine told me to have media player open in the background while I play. The reason being is that it will load and keep the necessary driver files in ram.
I have 8 gigs of ram and a 23in monitor, so I do not know if it will make a difference or not or how that really works. I know there is a chunk of ram that is reserverd I think for talking to the OS and asking for the files, but not sure what files are stored on it.
AFAIK opening up Windows Media Player while playing games will actually hinder performance, as it will take CPU cycles and RAM to keep the program open.
Windows Media player has nothing to do with driver's or ram (besides taking up ram when it's on). Driver's are handled by your operating system.
If anything, something like Gamebooster would do the job (it closes unnecessary services and programs when you want to play a game), however you could do these changes yourself, but gamebooster puts it in 1 nice little spot.