On my trusty T42 (bought ~10 years ago for about 30 euros) the GPU finally died last winter (heavy, unreadable screen flicker during every slightly more intensive task). It has an IPS panel which itself still seems to be in order, though. Luckily, I accidentally saw a similar one (no IPS, though) for 26 euros, so I'm rocking again.
Those 4:3 screens and T4x series keyboards are really hard to let go, and if your activities allow for more text-oriented operating systems (I installed 9front on mine, but used to be a dedicated Tinycore Linux user, and the T42 is also nice with the various open source DOSes we have these days), they're still perfectly capable machines for 90% of relevant tasks. CF cards make very nice poor man's SSDs, so the machine is also very quiet with this setup, so far the fan rarely turns on.
As for my previous T42, I think I really squeezed a lot out of it, including using it to produce (and, on a few occasions, record live) 1-hour radio shows for my country's public broadcasting (honored to contribute to a "landmark" series where high production quality is a must). It was always fun to think that here I am, working on a 30€ 15-year-old machine, whereas other guys are doing their exact same montages on 2000€ Macbooks -- and regarding the resulting production, the radio listener will notice no difference whatsoever. :)
Obviously, though, this is a geek thing, those Macs probably do make a lot of sense for serious audio production.
It's completely crazy, though, how you can get a more or less perfectly working (!) Thinkpad for 25-30 euros, whereas that same brand new machine cost something like 2k in 2007.