Assuming you are going for a laptop for portability, you might want to consider weight and battery life, also what you need built-in or as add-on & carry-round.
Is it more important to have a light, slimline machine without parallel port (do you have a need to print - do you have a USB printer?) or floppy drive? Do you need a docking station for home or office use?
Consider also DVD rather than CD drive - better still CD-RW which is one of those things you wonder how you ever did without!
Check the number of USB ports and PCMCIA / PC card slots against your needs
P4 / Centrino - go to intel's website to read about what it can do for you, and then decide if it is worth a premium.
I suggest you find a magazine (printed or on-line) with comparative group test reviews to help narrowing down your choice. PC Magazine (VNU) used also do a reliability survey of manufacturers which might be worth looking for.
If you are going to support the laptop yourself, go to the manufacturer's support website and see how easy it is to get information, drivers etc.
Bottom line - set a budget and buy the best spec you can afford that answers your requirements
This isn't a recommendation, but I have had company laptops from IBM, Dell, Compaq/HP (current) and Toshiba, and I always preferred Toshiba to use, but IBM, Dell and Compaq's support sites are better.
The last Tosh I had is now 6 years old and still going strong (well as strong as a PII 266 can go
)
SD