I use MobiPocket MobiReader to read eBooks on my Touch Pro. Works awesome. You install the PPC apps and there's a windows app too. The Windows app will convert PDFs and a few other formats to a PRC file. The only time I've ran into a problem is when I've found a book in the Microsoft Reader format, .LIT. That requires a few extra steps to convert to the LIT to another format that MobiReader is able to convert.
http://www.mobipocket.com