Got some more comments about issues other people have had with the D600 in my previous post:
I can only really comment on the heat issue. I haven't found the D600 to be very hot. I've used a number of laptops over the years that were hotter such as the IBM 600E. Plus the fan control on the D600 is pretty good.
The complaint with heat on the D600 seems to be at the keyboard and not on the bottom which might be a result of the lower width of that laptop vs previous generations. A partner has an IBM X31 and that thing also runs pretty warm.
One thing I have noticed in regards to the D600 and perhaps this isn't localized to this particular laptop, but the wireless does have issues.
We have an NT domain at work and a script is supposed to run when you log in. If this script doesn't run, the users don't get access to our document management system among other things. The wireless card doesn't detect and connect to the network unless the laptop has been on for a couple of minutes, so the first time a user boots up in the morning, they either have to wait a few minutes after getting the Ctrl-Alt-Del to login prompt for the wireless card to connect or they have to log in, wait for the wireless card to connect and then log out and back in. Doing a restart won't work as that just makes the wireless card have to find the network and connect all over again.
Even more annoying is that on some of the laptops, even if the user is connected via Ethernet cable, the wireless connection takes precedence so that if the wireless card is enabled, the system won't properly log on using the Ethernet connection. This isn't how XP is supposed to function.
One of the laptops that I am talking about, I have had enough problems that I had to uninstall and reinstall the network card and wireless card drivers (the network card wasn't connecting at all).
Between the D600 and the other laptops that I've now connected through wireless, I haven't exactly gained confidence in the reliability of wireless networking.
Yes, I could set up the systems to wait for a network connection before starting windows after the user logs in, but the whole point of XP is the fast boot up time.