Over the years I've owned 2 thinkpads. If the HP that I'm using now wasn't such a great deal I would have bought another thinkpad.
I am a big fan of the way it handles being tossed around. I caried my first thinkpad (a Subnotebook) in a cheap shoulder bag every day on the NYC subway and it lasted 4 years before I upgraded.
Look for the lightest, smallest and longest battery life you can find in your budget. Check with your company also to see if they have an EEP program. That could save you 10%-20% alone. That with a easily searched for coupon could make for a great road warrior notebook.