That's not really an upgrade, more of a "side-grade", IMO. i.e. although there is some overlap -- Lightroom can do light editing like cropping and red eye reduction, while Elements can do some photo organization -- the two programs are designed for different things: Lightroom is primarily bulk/mass photo cataloging and processing app while Photoshop (Elements) is primarily an image editing app. Here's an old forum thread
that may help.
Having said that, have you considered Adobe's Photographer's bundle
? - Mark