How can I get more free system memory??

When I open activity monitor, it shows me as having about 6.0 MB of Free System memory. Is there any way I can increase this? Firefox freezes all of the time and I have to force quit. I'm pretty sure these two issues are related. I have some programs open, but they are just basic ones that I think I should be able to have open without having to force quit applications all of the time. (itunes, mail, etc.). Does anyone have any idea on how to maybe quit some background applications to get more free memory?
thanks,
Charlie

How much Ram (memory) is installed?

other than installing some new ram, try this little app..

http://www.apple.com/downloads/macosx/system_disk_utilities/ifreemem.html

Having at least 2GB of ram helps a lot. But also the combination of free and inactive memory is what is important. If both of those are low then you need more ram. But if not then you're ok.