Do you think users really cares about a html and css validated website

[MattF]

User wise, they generally couldn't give a toss as long as the page displays correctly in their browser.

From the coder side, however, it's a must, IMHO. Firstly, if you can't even be arsed to output clean, valid code, it doesn't speak volumes about your abilities with your code which isn't visible. Perfectionism is all or none. Secondly, invalid output code will cause you more problems in the long run. You have absolutely no idea how a parser will interpret invalid code, and you will probably drive yourself to distraction at some point trying to get the output to render equally in various browsers. Some browsers will give you grief no matter how good your code, (that is an IE dig, as you probably guessed), but generally any differences in rendering are easily sorted when the output is valid. Not always so with invalid code.