I've been suprised at the number of people who've asked me this question in the last couple of days. As I've mentioned previously I moved over to Windows 7 as my main O/S back in October with the PDC/WinHec M3 pre-Beta. A couple of days ago I moved up to the official public beta 1 which is build 7000.
Viewing the available font list is pretty straight forward - there are 133 built-in fonts in the beta - simply type "font" at the Start menu - this will take you into Control Panel>fonts (unless you have index documents/emails with the word "font" in - in that case you'll have to pick the font applet from the search result list) which will reveal the following:
If you double click on one of the fonts then you'll see a subset of fonts on the screen - the members of the corresponding font family, double clicking again will give you a screen like the following illustrating the font: