It has been said many times but it's one of those things that can never be said enough. We do need to take likelihood of the font you want to use installed on other systems into account.

As I mention in my hairy list of 'hood code, try to include either three font choices with one being a basic, or two with both being moderately basic or oft' found fonts.

For instance, I like the look of Trebuchet MS. I also love the look of Majandra GD (though the second especially is rare). I stick with Comic Sans MS alot because I know it's found on many pc's (though not too many macs). So in coding, I often code it like this:

<div style="font-family: 'Maiandra GD','Trebuchet MS',Arial; color: #cc99ff">
The quick brown fox jumps over the lazy dog
</div>

Gives me this:

According to Visibone's Font Survey & statistics, only 26% will be able to see my chosen Maiandra GD. Of the remaining 74%, a shocking, whopping 96% will be able to see Trebuchet MS (including 92% MAC users!) and of the one or two people left that can't see either of these, it's literally guaranteed they will be able to view the Arial.