How long till a computer becomes outdated?

I'm in my freshman year of college now and got a powerbook. But was wondering, how long until i'll need to get a newer, advanced computer? How long do you take until you buy a new, replacement for your computer? I've heard some people say that in 5 years your computer will be outdated. I'm just trying to figure if i'll need a replacement before I graduate or not. Thanks for the help!

Depends on what you are using your system for. If you are using it for research and documentation creation. it should last you until graduate and then some. As for your system be outdated,that is a relative term. It is better to look at use.

Nobody can really answer that effectively. How obsolete a computer becomes depends heavily on each person's particular use. I personally keep my computers for around 3-4 years before I replace them. I don't necessarily need to replace them, but I sometimes do. Sometimes I will keep them longer. I had a G3 Lombard PowerBook for almost 8 years before I finally sold it. I had used it daily and never had a problem with it. I had equally as old iMacs. It is all a matter of personal use and preference.

Technically your computer is outdated as soon as Apple makes an update on it (no matter how small). What you want to know is when it becomes obsolete, which as D3v1L8OY and rMan have said all depends on what you use it for.