My typist tells me that if she sends my manuscript electronically, the formatting will not be preserved. How can we correct for this and does it involve PDF?

Depends on the nature of the document, the nature of the formatting, and how the document will be used by the recipient. If both sender & recipient have the program that created the file, and have the same fonts, the formatting will be the same on both ends. Your typist is correct only if it's the case that the recipient tries to open the file in a different application and/or the fonts used to create the document are not available to the recipient.

There are several advantages to using PDF files: the formatting will be the same no matter the platform (you can embed fonts in a PDF file). Print shops are used to dealing with PDF files so it's a good format for exchanging information. If you're using Macintosh OS X, you can generate PDF files from any application when you print it. If you're using Windows, you'll need a third party app to create PDF files. The bad news is that Adobe Acrobat Standard will set you back around 300USD. The good news is that there are cheaper alternatives available for windows; search for "create pdf file" at Free Software Downloads and Software Reviews - Download.com.

Vasily