HP and Dell are definitely out. Historically, these brands have had a high number of hardware failures. Additionally, their customer service situation is difficult to deal with. gethuman helps, but you shouldn't have to deal with everything in the first place. Lenovo is better than Toshiba, but neither is as well built as a fujitsu (this is the one I recommend the most if you buy windows). Asus doesn't do too bad a job (certainly better than acer) and I haven't seen a Gateway in years for good reason.
But honestly, if you are going to get a windows computer, you should really just build one yourself. If you can't do that, then you should probably lean towards a Mac. People will say that's extreme, but the simple truth is this:
many windows computers are not built specifically to run windows software. This matters because certain technical interactions wear down parts, making them more prone to failure. Macs rarely, if ever, have this problem because their OS is built for their hardware and vice-versa. They may look better spec-wise than a mac, and they may be cheaper, but the consistency, quality, and often times customer service is not there. That being said, the WWDC is this coming week and the landscape may change with Tim Cook as CEO instead of Steve Jobs, but I doubt it will change all that significantly. They did have their first quality downgrade with Siri being sent out in beta, but that is a very exceptional case.
I'm assuming that if you are asking this question, you aren't even considering Linux. I love linux, but at this point in your life you should probably just stay away from it (unless you begin learning a lot more about computers and even coding).
My Recommendation for most people: BUY A MAC. I know it feels like a cult, but you just need to get over that and go for it. For the peace of mind it provides it is far and away the best deal the average person can get on a computer. The integration with other Apple products also does not hurt. In law school you should really be looking for a computer that 1. Never breaks 2. Runs a generally intuitive OS, and 3. Has a strong battery life. I grew up building computers with my dad. I've had pretty much every brand at one point or another. NO ONE has been able to take my abuse like Apple. It is simply a quality product.
Bearing in mind the WWDC is this week, alongside several other technology jumps this summer, sites like engadget, gizmodo, etc. have already called this the worst time in the history of computers to buy a laptop:
http://gizmodo.com/5916005/theres-never ... y-a-laptop . I personally, am waiting a week to see what Apple does before I decide to move forward. The rest of the field is rather predictable, if not open already, but Apple could be coming out with some cool stuff; retina display (slim chance though), ssds for the pros, slimmer bodies, better battery due to the ssd, possible siri integration, mountain lion osx, etc.
I will probably end up buying one of the new pros given that I'm not overly surprised with the WWDC news. They are high quality instruments and are perfect for my needs across the board.
now to answer your questions regarding tiers, I would do this:
500: I would not expect anything from a laptop at this price. It is probably going to crap out at some point. I would probably just buy a desktop and take notes on paper. If not that, I'm personally curious about the samsung chromebooks. I was able to try out the beta models a while back when google was giving them out and loved it for certain things. I can't remember if samsung made it at the time, but the machine was simple and nice. Excellent for old people, the inept, and people who have singular functions for their machine.
1000: Macbook Air
1500: Macbook Pro
2000: Souped up Macbook Pro