Let's not forget the standard Macbook, which is roughly equivalent to that Dell too.
http://www.apple.com/macbook/specs.html
A macbook of the same capacity would only cost a bit more than that Dell. It would have 40gb less hard drive space but a faster processor(2.2ghz), and the RAM is user serviceable. As long as you don't buy the RAM from apple the difference in cost between the two would be minimal.
My mom is thinking about getting one due to her current laptop getting pissy.
.... and also, is it possible to home-build a laptop? They don't strike me as very easy to make.