The first product to truly compete with Apple’s Aperture has been released and is only $199 for a limited time. It jumps to $299 after April 30th.
If you haven’t already tried it, there is a 30 day free trial posted. From photo experts the field is split pretty evenly about which product they prefer. Lightroom has some great features, and features very easy integration with Photoshop; Whereas Aperture features great integration with the iLife apps.
Lightroom did start off as simply an Apple product, and is a Universal Binary, but you can also purchase it for the PC now as well. Lightroom was designed for Windows XP, but does run on Vista with the exception of the CD/DVD burning feature.