Adobe Lightroom 3 or CS5 best for PP with XZ-1?

Along with many of you, I'm anxiously awaiting delivery of my XZ-1. In the meantime, my xmas gift from my wife - new HP PC running Windows 7 64bit - rendered my Photoshop investment (CS2 and CS3) worthless. I can get CS5 at the upgrade price of app $189, or - in the alternative - I was considering Lightroom 3, which would set me back app $250.00. Adobe advised me that they would NOT accept my CS3 Serial Number for upgrade pricing on Lightroom (I actually thought - given the circumstances - that they would render that courtesy).

Looking for practical advice, from real life use ... from reading all I could about Lightroom 3 on Adobe's site and elsewhere, it sounds like it may be preferable to CS5, but if CS5 can do everything Lightroom 3 can - and more - then the choice is simple; cheaper to upgrade to CS5.