For my first post, I am going to step in here...I own a 2001 corvette...have driven a 94 viper and have a 2003 viper on order. I love both of the cars. The corvette however is much more refined of a car then the viper. The active handling system in the later model c5's is something that the viper could benefit from but lacks. It is excellent for less experienced driver (as most people who buy sports cars are). The brakes in the corvette are much better then the vipers. The corvette doesn't feel as "BRUTE" as the viper and this allows for a more comfortable ride especially on longer trips. The viper is a very pwerful car though and it requires a good driver to actually use the power and lay it down to the pavement. Of the maybe 8,000 vipers produced about 10% of them have crashed within 1000 miles (my estimate totally made that number up) The cars have a lot of power and you can feel it everytime you step on the gas.
As far as america's sports car goes I am going to have to side with the c5 due to sheer volume. The corvette can roll door to door with almost any production car on this planet (as can the viper) But the corvette is more accessible to the average american. Just my $.02