Simple. Take a screen shot of your webpage, then use the background eraser tool in Photoshop to get rid of the background.
Easier still, would be re-creating your marquee text completely in Photoshop, minus the background and any other distractions, then using an
<img> tag to place the PNG-24+transparency background (or PNG-32, as it's known in Fireworks), inside the
<div> where your title would otherwise be.
You can also make a non-transparent version for older browsers (like IE6), which don't support transparent images.
If you know a little PHP, you can even set up a script to detect the user agent (browser), then use the appropriate image, transparent image, or, for modern browsers, lack of image, and instead, use of an actual font.