XHTML/CSS validation

Thought I should check how well I did some html/css/javascript work. Used W3C validation service to check my (X)HTML and W3C CSS validation service to validate the CSS part. I got a pass :) Did though get a comment on my use of fonts, its was recommended that I provide a generic font family as a fall-back. This sent me on a search for more info on fonts, found a good reference which explained the five different generic font families, I decided on sherif.