I love my Thinkpad. It's had all sorts of tortuous treatment and just keeps on ticking. It was kind of amazing the first time I spilt water on it to have it drain out through the holes in the bottom of it and just keep going (I've also stepped on it, dropped it, etc; I'm actually very careful with my computers, but when you work with it 14+ hours a day for a few years, sooner or later you're going to do something stupid with it).

I have the x61, which is great. If I were buying one today, I'd probably get one of the x300 series; they seem to have a slower CPU than the x61 (and x200), but faster graphics, and better screen resolution. CPUs are fast enough that it almost doesn't matter these days (for web dev anyway), but faster graphics are always good -- I really feel the screen redraw when switching desktops with it plugged into my 26 inch monitor (still, this machine is like, 2.5 years old).

For me, having a lightweight and portable machine is pretty key. I also have an MBP (15 inch), but it's so much more work to throw into my backpack and lug around. I always have my Thinkpad with me, which is a huge part of what makes it valuable.

... Man, I am such a fanboy! :)