Actually, pwWebspeak is no longer produced. My personal recommendation, if you want to try a web site using actual access software is to download a screen reader such as JAWS for Windows or Windoweyes and try it with Internet Explorer. Both of these programs have special modes for presenting the page to the user, making use of Microsoft Active Accessibility to decolumnize the page and present it in a special buffer that can be moved through much like a word processor. This is how most blind people access the web.
My personal experience is that these programs handle things like frames, tables and the like a lot better then the W3C would make it sound. Quite frankly, if you use good HTML and common sense, your page will probably work just fine.
With regards to Bobby, while it is a great tool, Bobby is far from the definitive word on accessibility. Just because a page is bobby approved does not mean it is totally accessible, and just because a page is not bobby approved doesn't mean it is unusable by someone with a disability.