Allan is right about opening the task manager. (As well as the rest.)
Right click on the taskbar and select task manager. When it opens go to "processes". In the bottom left corner select "show all users". (Don't worry if it doesn't match what I said exactly...I'm writing this in Linux so can't check at the moment.) You will need to be admin to do this.
Once open and showing all processes you'll have a good idea what's running while idle. You can then go to the top and change the view of the columns. I tend to add the file path and a few others so I can see the files location and command string used. Be careful not to kill any items that are needed or your system will reboot or crash. Look for things like your video card driver helpers or ctfmon that although handy aren't really required. Look them up in Google at a few places to make sure you know what its for then try killing them, but only one at a time to ensure results are as expected.
Be aware that 2GB of RAM is nothing these days. I would expect most of it to be used on a Windows 7 system with a typical install setup. You can always see about making changes to your page file to help balance things a bit more. Although I've never used it myself I understand that others have used readyboost and a 2GB USB stick with some performance improvement. (Not looking to debate this just pointing out options.)
I tend to turn off a lot of services and processes I don't need or want. I usually keep in the 30 running processes range. It depends how many bells and whistles you want.
You can also go here for an excellent guide to what does what and which are safe to disable.http://www.blackviper.com/