I bought a powerbook fairly recently and was starting to getting pretty ticked off with the way Tiger was performing with 512MB RAM. I don't really consider myself a power user seeing as i've only been using a Mac for about 3 months but the number of beach balls I was seeing was unacceptable. I decided to fork out the money for an extra 1GB of RAM. I initially ordered it through the Corsair website as it was only £97 inc. delivery which I thought was a bargain. Lo and behold, upon arrival they had sent me the wrong RAM. I decided to turn to trusty old Crucial. I paid £130 for 1GB of RAM but at least it was correct. The result, the RAM has made a world of difference its almost like a new OS and computer. Dashboard widgets show up in an instant and there is no waiting time for them to be updated (I have about 16 widgets), loading up a number of high-res images in my web browser simultaneously no longer grinds my mac to a halt, iPhoto loads in an instant. I was after stability more than speed but I ended up geting both. If I could, I would add even more RAM! Just my 2c.