well you dont want 1meg of ram (thats only 1 megabyte)
Assuming that the "3.7 GIG" is your CPU speed??
IMO you allready have plenty ram in your system.
Your videocard, I guess is "powered" or "built" by ATi and is in the 9600 series, in anycase it has plenty of ram on that too and the ATI9600 series are very good cards.
What size(s) are your harddisk drive(s)?
And is there more disk accessing than usual while you have these "laggy moments"?
You probably should tweak Windows not to control your page file, but define the min|max size yourself.
You might also want to disable your Antivirus/Spyware Sweeper and other diskaccessing tasks you may have running in the backgroud while playing heavy resource eating games.
And finally try defrag your disk(s)
If you dont have a spyware too installed, you should get one as spyware easilly can drain your systems power.