My 700MHz iMac has 256mb of ram which is not enough, sometimes there is a good delay in opening programs and it's hard to oepn 2 programs at a time. Considering I really use the iMac just for web surfing and to write a letter now and then is adding an extra 256mb for a total of 512mb enough or should I go for an extra 512 mb for a total of 768mb. I can get the 256mb for $37 and the 512mg for $90 so there is a nice difference in price between the two. Will Tiger require more ram than Panther?