Site header as image...bad practice?

I’m a design newbie with a quick question. So I want to use an unusual font as a site header but I don’t want to undermine accessibility since I’m guessing most browsers won’t be able to read the font. So I’m thinking that I’ll simply turn the font into a jpg and post it as an image and then have an alt function with the header in a normal font. Is this workable or is it bad practice?

Ben

I like Cufon because it’s just so damn simple to implement, but the @font-face property in CSS3 is rapidly making Cufon, sIFR, and other replacement techniques obsolete. Coyier’s article is informative, but a bit dated.

A better practice is to use css text replacement. The code is almost exactly the same as if it were live text.