If you're inclined towards Fedora, its a solid distro to use... for the wireless aspect of the laptop, the driver isn't in the default kernel yet.
http://sourceforge.net/projects/ipw2100/
Almost certainly everything else is there... heck, Jeremy (LQ Jeremy), is running a T42 right next to me... right now, at LWE UK, on a stock FC2 install and he didn't have to do any monkeying.
Fedora Core 2 has a solid base with 2.6, you'll get all the ACPI support you need, and pretty much any current distro can do a centrino properly.
Cheers,
Finegan