How much of years an ...

Hola all.
Previously, I have asked a question about upgrading Apple computers and got it is somehow a difficult option (except for RAM).
It is hard (or impossible, I'm not sure) to upgrade the processor and ....
My question here is :
How much of years an apple computer remains -valid- ? 2 years ? 4 ?
Thanks.

My wife's machine was new in 1999 and she's been making sounds about wanting a replacement. My desktop machine was new in 2001 and it's still fine. I replaced my 1998 notebook last year.

I think four years is probably about right for use as a primary machine; they can last longer for casual use.

Macs seem to have a longer useful lifetime, in my opinion. All of my machines could be termed "older" but are still going strong for their usages. They include:

At home:

Powermac G4 dual-867MHz desktop: web application development, video editing, DVD authoring, Tomcat server, CVS repository, iTunes server (this is the machine which houses my music collection (20G) and streams it to the other Macs in the house as well as the TiVos), documentation authoring.

iBook G3 500MHz: e-mail and browsing while lounging in front of the TV, web app development, documentation authoring.

iMac indigo G3 300MHz: kitchen recipe database, e-mail, browsing recipes and other sites while waiting for the sauce to reduce.

At work:

iMac DV G3 400MHz: web server (Tomcat), documentation repository, web application testing.

All are "older" machines that still have years of useful lifetime to them.

I have a G4 PowerBook (866Mhz, 2 years old nearly) and generally it's still pretty snappy, although I do wish for something faster when doing Java development. I'm in no rush to upgrade though - will wait until there's a dual G4 or single G5 PowerBook on the market.