Just been through this process myself, I had to replace an Acer TravelMate (possibly the worst bit of junk that I have ever spent coin on - it lasted just over a year before falling to bits, my previous Compaq lasted five times that, and had a much harder life).
Finally settled on a Toshiba Satellite Pro - amazing bit of kit, well inside your budget, built like a tank, nice keyboard, clear screen, 2MB RAM and a huge hard drive... model is A200HD-1U4 CORE 2 DUO T7500P, 2GB RAM, 200GB HD, HDDVD (that bit may have been upgraded a tad now, since Tosh have given up on HDDVD and gone to BluRay).
New model looks like
this
Just get XP for it, and take off Vista, which just eats hard drive space and slooooooooooooooows it down....
Hope this helps!
TA