[Chris Martin]

I’ve been checking into this myself and what I found in the adobe forums is that the font preview in the panels is a feature of the Mac version of illustrator only. PC users must go to Type>Font for a preview.

That being said, I find that if I don’t know what font I want to use and I want to see how my text will look with many different fonts quickly, I select the text object i am working on with either selection tool then click on the font name in the character panel (not the pull down arrow, just click the font name so it is highlighted), then use your arrow up or down keys and you will see your actual text scroll through the different fonts quickly.