I have a T23 with a 1GHz P3 and a hefty 256GB of RAM - it originally came with Win2K!
Although the last battery I bought isn't good for more than about 20 minutes any more - and I have other newer computers I use more often - I still keep the old T23 around. Why? Because it makes a good test bed for Linux distros I want to try. Right now I'm dual-booting the latest Mint and Ubuntu to compare them and try out different software configurations, before making changes to my work laptop (an i7 machine running Ubuntu 10.04, the last LTS version). I feel more daring with the old machine, because if I screw something up it's no problem - painless learning. Stuff that works I can then also do in greater confidence on my main work laptop.
The T23 is not as fast as my newer machines, but I see this as a virtue - as a test bed, if something runs acceptably well on it, I know that same software will fly on my better boxes.
To my continued surprise, however, most of what I've tried on the old Thinkpad works pretty well. I could use it as my main machine in a pinch, and have had to do so on one occasion without problems. The biggest shortcoming of the old T23 is the anemic video performance, which I have been able to partly offset by disabling most of the eye candy in the newer distros.
So, to speak to your question: my experience would indicate that you'll do fine with your T42 for years to come. If future versions of mainstream distros like Ubuntu, Mint, or PCLinuxOS ever become too much for it to run (they will not be at this time), just cut back your video settings, or drop back to a light distro like Knoppix or Puppy Linux. They run great on old hardware - I used to have an ancient ThinkPad 390 laptop that ran Knoppix great, and that was only about 5 years ago.
ThinkPads are great hardware, and long outlive the dated Windows software most of them came with. So I think you're on the right track to extend the useful life of your T42 with Linux. I switched to Linux on my business machines several years ago and am much happier than I was using Windows. (In addition to the T23, there are two Dell business desktops of 2004 vintage, an IBM workstation from 2005, and my aforementioned new laptop, all on Ubuntu 10.04 LTS.)
I may move up to the new LTS when it comes out next year; and that's also the beauty of Linux - you upgrade when you want to, to the distro & version that works best for you. Go for it! You're on the right track.
answered Nov 06 '11 at 08:20
Perhaps not Mint, but Linux will always keep that machine alive as you can make Linux as large or as small as you need it. LINUX=FREEDOM
answered Nov 06 '11 at 13:33
Heck I am running a thinkpad R32 with a 1.6GHZ cpu from intel and 1 gig of ram for the last 4-5 years and its working perfectly over here. Just updated the distro over on it. and I have no complaints over here.
answered Nov 06 '11 at 16:30