I've just sold my 2006 HCH and will now be buying the 2008 Prius, so I can give you the options.

Both vehicles are great, except....

The HCH is better suited for lots of highway / freeway driving (smaller ptrol and electric motors)

The Prius is better suited for stop-go city driving.

"They both give excellent economy when driven as indicated above, but overall the Prius wins". You have to work "very" hard to achieve the economy figures that Honda quotes - much easier with the Prius.

The HCH has more features for the money and is more "car" like

The HCH lacks grunt! 86Kw versus 107Kw for ther Prius. (Total combined power figures)

The HCH is smooth and cheaper.

The Prius is a little more "agricultural" in its feel on the road, but nice nontheless.

It's very difficult to get the HCH into electric motor only mode (if at all) - The Prius has an electric motor only button to force into this mode under 40Klm an hour. Great on the morning crawl to work!

I should have bought the Prius first up....sorry HCH owners out there.