LR5 won't run on Vista so you need to upgrade your OS to at least Windows 7.
Thank you, I missed that.
I'm switching from Windows to Mac, and I would like to use the Mac version of LR5. I'm using LR2.4 on Windows Vista now, and I thought my best route would to be upgrade to LR5 before switching. Now that I'm faced with upgrading Windows too, is there a better to switch?
You can go ahead and make the switch. The Windows version and the Mac version use the same catalog. Your biggest issue might be showing Lightroom where the images are located on the new computer.
On you need to do is make note of the serial number of your existing Lightroom. When you install an upgrade version on the Mac you will need your current serial number as well as the new one for Lightroom 5.
Thank you, I'll go that route.