Powerbook barrier

I’ve often waxed lyrical about my wonderful Powerbook G4 12″ laptop, but on the weekend I think I’ve finally hit it’s limit. I was working in Illustrator CS on an A3 poster design for a friend that included some largish photographs. The save time was pretty ordinary, but the load time for the application, and Photoshop CS for that matter, was even worse. I suspect this is mostly a RAM issue (I’ve got 396MB), so I’m going to upgrade to at least 768MB and see how that goes. Hopefully it’ll make a world of difference (I would expect it would too – my work PC has 512MB and handles large files reasonably well). Does anyone know if this is a good price?