On all the games except EoSD (for some arcane reason I have no idea why) run fine at 60 FPS at 1 GB RAM (plus 4 GB swap file), 1.46 GHz processor, running two Firefox windows (with a combined total of 20 active tabs and four inactive tabs - don't ask), one VLC window (paused), one Word 2k3 window, iTunes (playing music), controller software, and all of the fun little stuff in the background simultaneously.
IIRC, Firefox is a huge resource hog, even more if there's a ton of tabs. So...
You'd do okay with >1GB of RAM (the computers at school run them reliably at around 512 MB), though I'm not sure on processor statistics.