At the end of last year I finally got around to playing with the demo version of Macromedia Captivate, and my initial impression was quite favorable. In that brief review I promised that I would create identical tutorials in each tool so we could all compare the output. They're not pretty or pedagogically sound; I just wanted to get something done for comparison's sake. Here you go!
Captivate - ERIC Thesaurus
ViewletBuilder Pro - ERIC Thesaurus
My side-by-side impressions? I do still like ViewletBuilder, and it's already bought and paid for. It took me less time to build the ViewletBuilder tutorial, but I am inimately familiar with it, while this was my first kick at Captivate. I've got to say either product can get the job done. They both offer similar quiz features (I haven't looked at all the advanced features in Captivate yet, so there may be more there). Captivate offers a lot more bells and whistles, including fancy animation and of course integration with the full version of Flash and other Macromedia products.
Cost: Captivate is $199 US for an educational license, ViewletBuilder Pro is $399 US for an educational license. Hmmm, that's not good - I'm pretty sure that's more than I paid for the product back in 2001, though it has improved significantly. ViewletBuilder Standard is available with an educational price of $239, but it doesn't offer the quiz or interactivity features. I noticed while I was surfing the Qarbon website that they are offering a deal to upgrade from any of the competitors (Camtasia, Captivate, Robodemo, or Turbodemo) to ViewletBuilder Pro for $200, and I'll bet if you really pushed you might be able to get an educational discount on that price too.
Trial: You can try both products for free if you like - Captivate offers the full version for 30 days, after which it will cease to work, and ViewletBuilder offers the full version also for 30 days, but the products created will have a superimposed watermark until you pay for the licensed version, which will remove them.
Compatibility: Both products work on Windows 2K or XP. ViewletBuilder works back to Win98, and also works on some Linux and Solaris platforms (probably not a huge market). Unfortunately, neither appear to work on the Mac platform.
Oh, as I was uploading I noticed one other thing you might be interested in - the ViewletBuilder .swf file (Flash) was just about exactly half the size as the .swf file Captivate created. I suspect the extra size comes from the animated text I used in the Captivate presentation.