Anywho, I've got a T40 that I've been using for a year or so (1.5 P-M, 512 MB DDR, 40 GB HD, DVD-ROM/CD-RW, Radeon 7500 mobility, 14.1" 1024x768). The cooling fan remains off most of the time, but it can be somewhat noisy when it spins up. The hard drive is fairly quiet, but it makes a slight hissing noise when spun up.
Other things... Best keyboard I've used in a laptop, and typical IBM build quality. Hell, it's even got a little LED above the display you can turn on that shines onto the keyboard.
Battery life is very good (I've had 4 hours, easily), and the combo drive, while not all that quiet, works fairly well. It's fairly light, too, at about 4 or 5 pounds (IIRC). Oh, and the IBM Predesktop Area (i.e., uberfancy BIOS) is useful for various things, like diagnostics. 'tis a great laptop, and the current T42 should be just as good.