Also, your options may vary according to whether you care about any of the following points:
1. weight and size (do you want to have your laptop with you all the time and feel light on the go)
2. battery working time (do you want to work on batteries for long periods of time)
3. screen quality and brightness (be prepared that laptops in general are backwards from desktops in this regard)
4. keyboard quality and size
5. drive size, longevity and durability
6. network acess options (some laptops have cellular modem built-in, so theoretically you will be able to stay connected really anywhere; need that?)

If you don't care, that's easier for you. If you do care (like me) - then you should do some serious research and, frankly, can still have some backwards thoughts after your purchase.

I was in the situation similar to yours, i.e. I wanted a laptop to be able to learn programming in different places. As a long time computer user, I had my specific preferences:
1. minimum weight and size; I want to have my laptop with me all the time and not feel constrained with it
2. maximum battery working time. noone thinks that a cell phone that is only able to work half of a day is ok, why is it ok for laptop? in the meanwhile, I want a laptop with a battery life as long as possible.
3. i wasn't concerned about screen quality, as I don't want to edit images on my laptop but mainly work with text and programs. but now I think screen of my current IBM X60s could really be brighter. it's ok to use in rooms, when not under direct sunlight, but not with the minimum brightness settings. viewing angles are decent, but cold be better too. in general, from what i gather, IBM/Lenovo is very conservative in their choice of screens. In non-Apple world, the only company whose laptops' get frequent praise for their screens is Sony.
4. i'm very used to desktop keyboard, so the more I was inclined to buy a ThinkPad: their keyboards are often said to be of great quality and the key placement is the closest to desktop that I've seen.
5. i don't need file storage of great size, but I really want to be sure that my hard drive won't break. so I chose SSD (these models don't come with them standard, the hdd was upgraded manually by the prev. owner)
6. i wanted to have cellular modem built-in, so I went a bit out of the way to get it: here in Russia the models with WWAN are not sold, so I bought import model and had to unlock it with a special program. It works now!
also:
I needed Windows. In fact I think that open-source OS is the wave of the future, but I don't ride that wave. I'm deeply rooted in Windows. XP is fine for me, don't need Vista.
mat screen.
4x3 screen proportions.
lower dpi screen, please. 1024x768 on 12" is ok (107 dpi), but higher resolution screens have higher dpi - I have problems with those. I have good vision, but I don't want to strain it.

So, after careful consideration, that brought me the following laptop:
IBM X60s (1702-64M) 12.1 1024x768 | CD 1.66LV | 2GB | 32GB SSD | BT+abg+WWAN(MC8755) [1,5 kg, 6..8 hours of mild work]
I bought it from a ThinkPads forum member in Australia. I'm generally quite happy with it, but I'm still yet to get adjusted to some issues like the smallish keyboard (maybe a light 14" would be better? or should I just adjust to this one?) and not very bright screen (it's ok in the room, but when I'm on a bus and there's sunshine in the street and the bus turns - oops, I can't see anything anymore :) - maybe a Sony would be better)