I'm with lawgirl in terms of wanting more information. It's relatively clear that T43 has a bit more tech behind it. It's a bit faster, newer, etc. I think it'll be available longer, and probably supported better in the long run. Were it not for the fan noise, I wonder if there'd be any question over the T42.
Personally, after all I've read, t's not even near clear to me what's up with the fan. I have read (here) that it's quiet, loud, low pitched, high pitched, louder than the t42, only loud at boot, quiet, totally quiet, blends with background noise, quiet under load, loud at idle, loud all the time, etc.
I sure wish there were a definitive thread on the whole fan thing with with some sort of objective measurements on the sound levels. (I remember that when I was shopping for my computer case, folks actually did decibel tests) The number of threads on fan noise in my mind makes it seem (perhaps artificially) like this is really common and significant problem with the T43.
I sit in classrooms a lot and I sit in business meeting rooms a lot, and I couldn't have the T43 going off as loudly as some people here are claiming.
FYI, I have looked around, and frankly unless I was a really loyal Thinkpad customer, and if I chose against the T43, I'd look at the new HP's rather than go with the older tech in the T42. The
HP 6230 has the same magnesium casing, and sturdiness, and all the same technology as the T43 at similar prices, and I haven't read any complaints about noise and heat with them. It's the same exact form factor, and It even has a slightly recessed keyboard to prevent screen scratches from the keys and pointer stick. (No Thinklight or Fingerprint though) As best I can tell the 6230 is meant to be the equal competitor to the T43.
All things considered, I'd prefer the T43 if this fan noise thing wasn't actually a problem. I am not really the type to buy something I am likely to return though, and I just don't have enough info to decide to pull the trigger as I have seen some folks here say.