I wish I had enough money to buy you all an imac for giving me the advice. I use the machine for my small business.

My current Powerbook G4 cost me $2800 plus tax in 2004. It has been an amazingly reliable machine. The last computer that I had before that was a Gateway. It was obsolete a few months after I bought it and completely useless about 1 year after that.
My new camera shoots very large files and my Powerbook takes some time to handle them. Therefore it is time to upgrade.

Based on my calculations, my Powerbook cost me about $50 a month to own(so far).
I believe if I don't spend the money properly the first time I will have to make an additional purchase which will cost me far more money than the original costs of the upgrades.