The most common problem is the battery conking out after a year or so, and then the replacement choice is either a ridiculously expensive one from Dell (which costs a third of the laptop itself!) or a cheap Chinese gamble from ebay. The screen hinges also break sooner than later.
Still, I think on the cheaper end, Dell laptops are better than Acer and Toshiba. Their keyboards are not amazing but at least they don't try to do any cute stunts with them. The Vostro is surprisingly well built.
Shame the Ubuntu version is not available in the UK (or maybe I just failed their website easter egg hunt).
I don't think they are available in Brazil either and, in any case, the keyboard layout is not to my taste.
The specs on the Vostro 1440 don't seem much different than the Inspiron 1420N I bought with Ubuntu 5 years ago.
I have nothing but good things to say about Dell computers. Of course, I am a bit careful not to choose ATI or Nvidia graphics or anything that seems designed to run only Windows. The v131 I'm using now works perfectly (and came with Ubuntu preinstalled). Having a version that comes preinstalled with Linux is a good indicator the machine will work properly with it.