I'm using a 1Ghz iMac that has only 256MB of RAM, which I am told is not enough for running Mac OS X really well. Under typical operation, I have anywhere from 5-25MB of RAM free according to my activity monitor. If I was to add some more, it would probably be a 512MB module. How much will this really help? If anyone has had an experience upgrading from 256MB (or something) and could give me an idea about how much it really helped, I'd appreciate it allot. Thanks.