Yes, you can use any T30 mobo with any CPU and any cooler.
BUT, from a 2.00GHz CPU onwards it is highly recommended, to use an assembly 2 mobo and an assembly 2 fan.
Most, if not all, people ignore the security chip. It's totally unimportant (I've never used it on any of my probably ten T30 machines).
All T30s come with 16MB ATI7500 GPU, and can drive both XGA and SXGA+.
With the latest BIOS, all T30s can also use 2x1GB PC2100 or PC2700 SODIMMs.
And with the NO-1802 hack, you can use any mini-PCI wifi card.
Thanks a lot for this detailed response. The computer would be for car diagnosis work, no need to have the fastest possible CPU (actually WLAN is not necessary either), should give me more options to choose motherboards then.