QReader is a freeware book reader that supports many common ebook format (Palm Doc, FB2, UMD, and TCR). Although you can not buy a commercial (DRM-ed) books, you can read a lot of freely available ebooks on the Internet. It has many features, such as searching and hyphenation. My only complain was that there is no option to add margin so that the text doesn’t get to close to the screen edges.
This program can be downloaded from http://www.qreader.com.