Rosetta is very, very, very bore. You will repeat the same words again and again and again and again. You will spend a lot of time. Around 40-50 hours/level: 200-250 hour hole curse. Yes, you will learn, but you can't learn something, if you spent 250 hours, at any course. And Rosetta needs you around computer: you can't walk and learn.
Pimsleur is really great courses. You need 15 hours at a level / 45 hours hole course (actually you will need more, you will need to repeat some lessons). And Pimsleur is interesting, you can walk and learn, and you will not boring. Pimsleur level 3 is worse than level 1 and 2. Level 3 is about business, meetings, companies, and all that business stuff. If you need that, great, if no, you can drop level 3. Level 1 and 2 really great. Probably after 30 hours of Pimsleur you will know a bit less than after 250 hours of Rosseta, but definitely not 10x times, not even 2x times. Rosetta is not worth it.
After two levels of Pimsleur you can try to find some spanish speakers at livemocha.com and talk with them.
And Pimsleur couses you also can find at TBP.
P. S. And I have not used Pimsleur or Rosetta to learn my English
I agree. I've demoed Rosetta & TellMeMore, which is similar. I'm a big fan of computers and what they can accomplish, but we own multiple mp3 players and only one modern computer. My kids have to do so much on this one machine already that I don't like the idea of another hour per day on an interactive foreign language program.