if you have money go with 512,
I am happy with 256 mb, eye candy turned off because I like simplicity, and some services are off too, like indexing, wave device for modem, some printing help services, and the system restore is off too..etc etc.
now I have Winamp running and Opera 6.0 with around 40 windows open and only 125 mb are being used,
once I had 512 mb ram but to tell you the truth I didn't notice difference, in fact 3dmark 2k1 was slower, becase more sticks of ram means more latency.
So, I reccomend 256 mb, don't let these people's bragging get to you.
(p.s. when I tryed 3 x 256 mb of ram on my Ex-motherboard Abit Kt7Raid, the board died, maybe the memory controller or something

so more doesn't always mean merrier)