Revit Architecture is my specialty. I have been researching this extensively. By budget is closer to the $1000 mark since I have a Core i7-860 desktop that I configured about a year ago for my intensive work.
I'm going to get the Lenovo ThinkPad T510 4314DEU (~ $1200)
Core i5-560M (2.66 GHz)
It upgrades from the base T510 by including 512 Mb dedicated graphics (Nvidia Quadro NVS3100M) instead of using Shared Memory (it's got Optimus hybrid technology actually), 1600 x 900 screen resolution, 9-cell battery claiming 10.4 hours (doubt it) - the 9-cell will stick out of the back of the notebook (which is not great design, but the added battery length is worth the trade-off for me), and it gives you a 3-year warranty instead of 1 year.
It is a 64-bit machine (critical for accessing the additional RAM), and while it only comes with 2 Gb RAM, I am going to max it out to 8 Gb for about $80.
Since your budget is higher, you could consider a ThinkPad W510 which introduces a Workstation Graphics Card (Quadro FRX 880M I think?).
I have heard about a lot of reliability complaints with all HP DV series notebooks. In fact, I had a DV6000 series that lasted just shy of 2 years when the motherboard took a total dump.
Hope this info helps.