It's my understanding, that with Verizon you cannot set the curve to always show the html content. You can, however (and only with 4.5), use the menu key when you are in the email and there is a feature to allow the email to be shown.
I've just switched from the Pearl to the Curve and had the same question.
I had to call Verizon Tech Support as they do not give us direct access to the BIS Servers. Though the rep told me to dial *228 option 1 if I need to do this again...but hell I am paying them $240/mo for 4 phones (2 berries) they should do it! :D
I followed the steps now I am just waiting for a new email to check out the HTML viewing! :D
All I've ever wanted was an honest week's pay for an honest day's work. - Steve Martin