Should I upgrade RAM?

Question

I have a 800 MHz G4 iBook with 640 MB of RAM running OS 10.3.9. It is a month or two shy of three years old. The computer (my first Mac) is still in great shape and works fine for nearly everything I do.
However, when I do things like import a video file into iMovie or try to convert a video from one format to another, it is painfully slow. Otherwise, the speed is fine for what I do. I put some thought into upgrading to a new Intel Mac, but I don't think it's the right time. I can really only afford a Mac Mini at this point and I'd prefer to stick with a laptop, plus this one issue doesn't see quite worth buying a new computer for.
So, my question is, is it worth upgrading the RAM on the iBook? Can I expect significant speed gains or would it be negligable? (Quite honestly, I'm not sure if it's the processor or RAM that's limiting me here) Also, does anyone know the max RAM I can fit into this model of iBook? I had thought that the 640 MB was the max, but a recent Macworld article had around 1 or 1.5 GB as the higher limit.
Thanks for the help!
iBook   Mac OS X (10.3.9)   800 MHz, 640 MB RAM, 40 GB HD

Answer 1

Can I expect significant speed gains or would it be negligable? (Quite honestly, I'm not sure if it's the processor or RAM that's limiting me here)
Open Utilities > Activity Monitor and click on the System Memory tab
The ratio of pageouts to pageins will be a good indicator of whether or not more RAM will be a big help. If pageouts are more than 10% of pageins, then more RAM will be a big help and take a load of the Virtual Memory system (which is mainly your hard disk).
If your pageouts are zero, more RAM isn't going to help much at all.
You can also use Activity Monitor to see how hard your CPU is working when you are doing video stuff -- although I would expect it to be pegged.