Bob gave you the important needs. Here are the details of those needs:
There are two 1.5 mhz Pentium M cpus out there ... the 705 Pentium M is the old original Centrino Banias standard with 1mb L2 system cache. I have one of these and they work great but it is crazy not to upgrade to the new Dothan line when it can cost only $50 if ordering custom.
HP and Dell are selling the 705 'fake Dothan' (all new 7xx branded Pentium M cpus were supposed to be Dothans but 'surprise' the lowest 705 is not.
Toshiba or some other manufacturers sell the 715 Dothan 1.5. If you want a notebook that has the 715 then go ahead and get that.
Otherwise, order the 725 Pentium M 1.6 mhz or higher. The 735 1.7 mhz is on many prebuilt notebooks in the stores. For the Compaq X1000 a Pentium M 725 Dothan is only $50 above the bogus 705 Banias 1.5. That is it if ordering custom. Retail price differences are much higher (as much as 400-500) as they load up the Pentium M Dothan 1.7 prebuilts with a DVD burner (+200), higher video memory, etc in comparison to the 705 (Banias) cpu with a DVD/CD-RW, less dedicated video, etc.
If you order custom you can avoid this large price difference by ordering what is a priority to you and getting less (save $200 on CD-RW/DVD instead of DVD burner) of what you don't need.
For HP custom notebooks the 755 Pentium 2.0 Dothan is $475 more than the 705. That is not worth it . And the 745 Pentium M 1.8 is too pricey also.
So, get the lowest Dothan CPU (715 or above) that you can and that is the best value. You will appreciate the 2mb L2 system cache (doubled from original Pentium M's.
And, yes, as Bob through in as a curve ball, try to avoid notebooks that have shared or integrated video memory.