When it comes to PDF readers, there are plenty to choose from, but few offer the versatility and speed of Foxit Reader. With a download size of less than 4MB, Foxit is extremely light and goes easy on system resources compared to Adobe's bloated Reader, yet it boasts an amazingly rich feature set. Some of its more notable features include an annotation tool, a text converter, interactive form filler, and much more.
Version 3.0 was just introduced last month, adding Firefox support for inline viewing of PDFs, while a new beta version for Linux machines was made available this week. You can find a complete list of features here. It's also worth noting that the Foxit interface mimics Adobe's, so you won't have to change your reading habits. Unless you're absolutely tied to Adobe Reader I suggest giving this freeware alternative a try. Foxit Reader supports all Windows versions from the unloved Millennium Edition all the way through Vista (and Windows 7 Beta) and it is compatible with PDF Standard 1.7.