Crystal reports does work with Peachtree, however it can get a little bit ugly.
In a Btrieve/Pervasive environment (Peachtree uses Btrieve 6.15, which is 10 year old technology) the .ddfs - data definition filess - are used to read the database.
Peachtree, in its infinite wisdom, has decided not to share all of the contents of the database with its users or even technical people. These fields that are not disclosed are start with the words "Dont Use" and are followed by a number. In addition to this, there are several entire tables that are not available through the .ddfs.
There are some built in special functions in Crystal reports for Peachtree (these are not there if you buy crystal "off the shelf") such as GetPeachRowAmount(), GetPeachCustomFieldHeading() and GetPeachQtyOnHand() These are all found under the "additional functions" area when writing a crystal reports formula. These functions help you get around some of the limitations listed above.
A fuller - and more expensive - workaround for this is PAWCOM -- http://www.multiwareinc.com/pawcom.htm -- which sells a pretty neat product which makes all of Peachtree's data available in a relational database format, within MS Access. The price as of this writing is $379.
My problem as a consultant is that the people who pay $300 for Peachtree rarely want to pay even more to buy a tool like PAWCOM, only to spend even more money for people like me to develop reports for them. Having said that, there are definately times that this is necessary.