I think you should narrow down your choises to:
Dell latitude D620 (14") or D820 (15.4")
Dell precision M65 (15.4")
IBM/Lenovo Thinkpad T60 (14")
Asus W3j (14")
Asus s96j (15.4")
Now in my opinion 14" is the best screen size for you... 15,4" are kinda big and heavier to carry around especially at the enviroment you're working..
That being said I'll tell you the pros and cons of the Asus W3j, dell D620 and the Thinkpad T60:
great video card
a bit heavy for a 14"
battery life could be better (because of the video card)
Best quality, best keyboard best service you can find
Mid range video card
its not good looking (but its not ugly)
worst build quality of the 3
Worst support (in theory) of the 3
So to sum things up, my final suggestion would be to go for the Thinkpad T60. I think you'll be glad you went for the highest quality product you could get, and the size, weight, keyboard .. its just amazing if you work on the go for a long period of time.
Here's how my config of it would be:http://www.pc.ibm.com/us/notebooks/t...s_byo_t60.html
Processor: Intel Core Duo processor T2400 (1.83GHz, 2MB L2, 667MHz FSB)
Operating system: Genuine Windows XP Home Edition
Display type: 14.1 inch SXGA+ (1400x1050) TFTMemory: 512MB PC2-5300 CL5 NP DDR2 SDRAM SODIMM
Graphics: 128MB ATI Mobility Radeon X1400Hard drive: 40 GB 5400 rpm SATA Hard Drive
Optical device: ThinkPad 24X/24X/24X/8X Max Combo Ultrabay Slim Drive
Integrated data/fax modem: 56K V.92 Designed Modem
Integrated Ethernet: Integrated Gigabit Ethernet
Integrated WiFi wireless LAN: Wi-Fi wireless upgradable and Bluetooth
Integrated WiFi wireless LAN adapters: Intel PRO/Wireless 3945ABG Mini-PCI Express Adapter
Battery: ThinkPad 9 Cell Li-Ion Battery
USB ports: 3 USB 2.0 (back)
Security: Embedded Security Subsystem 2.0 and Integrated fingerprint reader$1,479.00
Note that the Hd and RAM are the worst possible, because it will be be MUCH cheaper to upgrade them yourself then to buy directly from IBM..