Have you heard about XPS? As you can easily create XPS files yourself they could catch on pretty quick, giving Adobe some competition. Of course, lacking the fillable functionality of a PDF, they can't take the place of them.
The XML Paper Specification (XPS) makes modern documents possible for all. Simply put, XPS describes electronic paper in a way that can be read by hardware, read by software, and read by humans. With XPS, documents print better, can be shared easier, be archived with confidence, and are more secure.
Microsoft has integrated XPS-based technologies into the 2007 Microsoft Office system and the Microsoft Windows Vista operating system, but XPS itself is platform independent, openly published, and available royalty-free. Microsoft is using XPS to bring additional document value to its customers, its partners, and the computing industry.
Still running XP and not on Vista yet? Don't worry you can download what you need to view and generate XPS files here or pick up a copy of Office 2007 and get the add-in that lets you save files to PDF or XPS formats.