FWIW, the Lenovo line gets the highest marks from our users. Lenovo bought the IBM ThinkPad line a while back and they have continued to produce an excellent business class product. Their durability is rated somewhere close to what is known as a semi-rugged laptop. What that means is that it'll take the normal dings realized during inspection type activities, etc., but it is not rated for a 4 foot drop onto concrete, etc. Of course, we favor the Lenovo X61 with SuperView screen (the base option on this product) vs. the more expensive MultiView + MultiTouch screen simply because it performs better in the direct and indirect ambient lighting conditions common with appraisal activities. Generally, the X61 runs about $1500 and up depending on options. Most of our customers end up spending just under $2,000 including a drop/damage policy...

Here is a link to their site if one wants to look and shop.
http://tinyurl.com/2texdx Let me know if you'd like a suggested options list based on what others have found to work well. You can also find a couple of threads on this site about this particular unit and you'll see some recent purchasers' feedback.
[Edit 1] Here is a link to that thread here:
http://appraisersforum.com/showthread.php?t=131296
Anyway, MY advice is to MAKE SURE you can read the screen on your laptop in the environments in which it will be used. DO NOT rely on looking at it inside at a store. Take it outside if you're going to use it there! The glossy screens that look so sexy on most computers in the big box stores are almost unusable when you get into the sunlight. Even most screens with anti-glare treatments get really washed out when in indirect light (say, under the overhangs or in the car.) So, unless you are only going to use your laptop inside, be sure to pay attention to the screen. If it is only going to used inside, my narrow way of thinking begs me to ask why one would pay a premium for a laptop vs. a compact desktop unit... ;-)
[Edit 2] I have uploaded a cropped picture of two identical devices sitting side-by-side in an outdoor setting. The images are unaltered except for cropping and any artifacts caused by the jpeg lossy compression. Sorry for the smudged screen on the one on the right, LOL. If you look closely, you can still see the image on the screen, which is identical to the one on the left. The one on the left is not perfect but you can clearly see the differences. Anyone want to guess which one is the indoor screen and which is the outdoor screen? LOL. The devices, BTW, are at least 4 or 5 years old and the technology has improved.
Hope this helps! I have nothing to sell - I am simply reporting what we have observed ourselves and what our many, many users have reported over the years.