When you're using the text tool, there should be a pull-down menu on your editor bar (With the font and all) that has the options: None, Sharp, Crisp, Strong, Smooth and Windows/Windows LCD if you have Windows.
The only other thing I can think of, if it looks fine in Photoshop, is... do you have your browser zoomed in at all?
I ask because for a while I was trying to figure out why my graphics looks a lil blurry on TBT, but looked crystal clear in Photoshop and on Flickr. I eventually figured out that it was because by default, I have TBT zoomed in a lil bit. When I put it back to 100%, it's crystal clear.