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I have a:

MacBook Pro purchased January 2008
iMac purchased August 2007
Motion Computing Tablet PC purchased March 2004
Gateway Desktop purchased February 2003

All still work, although I have had the hard drive on the Gateway replaced. I try and get the most mileage I can from my computers.
 
My 700mhz iBook G3 is 5 years old. It's fine web browsing, listening to music, and doing other simple tasks. At this point it basically does everything In need it to do.
 
This computer, my youngest Mac, is four years old in March. But it's about time to replace this laptop and get a MacBook Pro. I'll probably hand this one down to my little bro.

We've also got a PowerMac G4 that's about 7 years old, a couple Performas over 10 years old, and a Mac SE getting close to 20 years old. They all work, though the Performa monitors are a little iffy.
 
1.25ghz Powerbook G4 - 4 years old
Powermac Cube - 7 years old
Powerbook G3 - almost 9

The powerbook is what I use every day. The cube has been used a few months over the past year when I didn't have a laptop and the G3 is still being used (with linux) by my roommate who ended up killing his computer.
 
my MBP is almost a year probably about 9 months old. my wifes laptop is roughly two years.
 
my powerbook is about 4 and half got it in Aug. 2004 and my imac is about a year and a half.
I'm holding out still school is over to get a new MBP or maybe even an air
 
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