Another vote for the ThinkPad (I currently have a T500 on order, the sixth ThinkPad I will have owned) - although the LED screen on the Dell is appealing.
You'll like the ThinkPad keyboard best however, IMO. And I use a Dell Latitude D630 almost as much as my ThinkPad.
"Meh" on the Toshiba - haven't considered them since their awful keyboard days in the late 90s.
I'm not excited about your tiny HD.
Oh, and since this appears to be an XP machine buy for light use (integrated graphics)...why are you wasting money on 4GB RAM? Spec 2 GB. Or spend the difference on a 250GB HD. Better use of your money for this kind of machine.