Absolutely. It is a big inconvenience to people with huge monitors to have to resize the page. It can also be a bit dodgy with some layouts. Little inconveniences, no matter how trivial, can actually affect people's opinions of your site.
Also, netbooks have odd resolutions which make it hard to design sites for. For example, I'm writing this at 1024x600.
It's not particularly hard nowadays either (in modern browsers), especially with min- and max-height in CSS, and the new gradients, etc in CSS3, so image scaling won't be as big a problem in the near future.
In response to the comment below, I think that the pros outweigh the cons in this particular case - IE6 is a problem everywhere. We just have to deal with it.
