I buy the same emac that you're thinking of getting and the 128mb ram just wasn't enough. Applications like Dreamweaver and Photoshop just ran too slow. In the end I ended up paying for 512mb extra ram. [Read my thread so see the problems I had].

From my limited experience I would say that 128mb isn't enough - you need at least 256mb but 512mb is better. You can go up to 1024mb on the 1ghz model.