An upgrade

I just mentioned that I am planning to buy an external hard drive, I forgot until a moment ago, when my laptop started acting up again, that I also need to upgrade the ram. I had photoshop cs3, dreamweaver cs3, thunderbird, firefox and smartftp open and my system suddenly went into stand still. I figure there might be some other problem but a ram upgrade is definitely in line. I have 1gb ram installed but it is never enough, my laptop can handle up to 4gb of ram, I might consider an additional 2gb upgrade if I have enough budget left over from the external hdd or might settle for an additional 1gb ram. Anything is better than 1gb, even a 512mb upgrade is looking great as of the moment.