Hola daveyboy. I agree with what Antonio has said: what you learn from Rocket Spanish or any other program will enable you to be understood throughout the Spanish-speaking world. In most parts of Spain, they pronounce a soft "c" as if it were "th", so that Barcelona sounds like Barthelona and cinco becomes thinco. But for the most part, the pronunciation is very similar, as is vocabulary.
If you want to hear the Spanish they speak in Spain, you may want to listen to the podcasts offered at Notes in Spanish: *__http://www.notesinspanish.com/__*. The podcasts are free, though the husband-and-wife team who provide them have also started to provide an optional worksheet for which they charge a very modest amount of money. You can see the details at the site.
The Notes in Spanish site is part of a larger site you may be interested in if you're planning to go to Spain: Notes from Spain: *__http://www.notesfromspain.com/__*
Another place to hear the Spanish from Spain is in the early episodes of Destinos: *__http://www.learner.org/resources/series75.html?pop=yes&vodid=276021&pid=366#__*
In the early episodes of this marvellous free telenovella that was designed to teach people Spanish, the main character goes to Spain and speaks with people there. Though she speaks Mexican Spanish, all the people she converses with while she's in Spain speak Castillian Spanish. She then moves on to other locales (Argentina, Puerto Rico, Mexico), so you'll hear lots of different accents.
I hope this helps.