Having read ur responses... here's what I think...
You could but... my MacBook has only 512 and it's running fine but some graphics things are sucky. Dashboard takes an extra SECOND to fly in. I'm maxing out my memory because OS X is holding 122MB to its self for the graphics and other things.
It's a trade off, if you want the thing to FLY, then u need the ram. if you are okay just dealing for a month or two then don't.
Also I got 1Gb of RAM from Newegg... 2 x 512MB for about 90 bucks.
macboyX