I recently bought a DVD from CycleFilm that is a "recon ride" of the 205 km L'Eroica course. An experienced racing cyclist (on an off-topic bike) talks you through the course and provides some useful tips. Some of the descents look a bit crazy, and in fact the DVD begins with two racing cyclists but only one makes it through!
The DVD is nicely-produced and good preparation, I think. I have written up a review of it on my blog here: http://www.tindonkey.com/2009/10/compleat-tour-de-basement-part-6-doing.html
Freezing in Ottawa, Ontario, Canada (-22C on the ride to work today)