Something I notice about stores that sell linux (any distro)
preinstalled is, the systems themselves are just as or more expensive
than Windows systems. I purchased a ThinkPad recently with a 2.0CPU, 1GB
ram, 80GB hd, 15" dvd-rw for $733.

If it were me what I would do is, go through this list
https://wiki.ubuntu.com/HardwareSupportMachinesLaptops?highlight=%
28laptop%29
find the laptop you like, and purchase that laptop. If you looks like it
will install - great!

Personally, I just setup a Gateway laptop for a customer and Ill
probably install ubuntu as a duel boot because its a nice little system.
For my own machine - I like Thinkpads.