Microsoft has released Microsoft Reader for Pocket PC 2.4.
This is a bug fix release primarily intended for users of handhelds running Windows Mobile 2003 and Windows Mobile 2003 Second Edition. While this version will run on all supported Pocket PC devices, Microsoft is only recommending that users of devices running these two versions of the operating system do this upgrade.
Upgrading will not require reactivation of the Pocket PC.
Microsoft Reader 2.4 is a free download from Microsoft's web site.
Ebooks can be purchased from a large number of stores, including Amazon.com, Fictionwise, Microsoft's ebook store, and many more.
Thanks to Larry for the tip.