i have no idea what i'm doing so probably.
All your programs run on RAM. That's the reason why even after deletion of some of the program's files the program will still run. (Take for instance Add-Ons, the Add-Ons seem to be moved to RAM; you will still have them in-game even after removing them).
You shouldn't need that much RAM unless you're hosting 2 servers, playing Battlefield 3 on a triple screen and having 10 other background programs.
I personally have 4 GB DDR3 RAM, I run BF:BC2 perfectly with all the following open: Maxthon 3 (RAM-Intensive) with 5 processes open, Steam, Maxthon Thunder Downloader Lite, Windows MSN, Antivirus (Durr) and some other background tasks on the processes list (Task Manager).
If you feel like a RAM-whore who wants to get a huge amount of RAM for no reason, you are free to get that. And why not remove all services & start-up programs to get the full of your RAM? (That actually just decreases around 250 MB ram usage I think [services], depends on System).
