will upgradeing to 10.4 gain much and is this the final upgrade

I think a lot of this is being covered on another topic you have going on this very same subject. It helps to only post once on a subject because you'll just find it's the same people answering the questions and it gets very confusing if we have to refer to multiple topics.

One thing I didn't see answered in the other is, an upgrade in system software almost always results in reduced performace.

I am also confused by your computer information. No Macbook Pro can run OSX 10.3.9. We cannot answer your question about final upgrade until we know which computer you are running. Don't answer here, answer in the other topic!