Twice now I've purchased a license for Parallels when they offered a discount and then within a month they come out with a newer version and no upgrade (other than the regular upgrade price that means I would have spent more on the new version than I would if I had just bought it straight out).
I only used the fist one for a couple times since it couldn't handle the USB device I needed Windows for (but Fusion does). So, I got the newer deal (right before 3.0 came out) just in case I needed a newer version, but got burned.

So, the bottom line is: if they offer a special to upgrade, run away, since they're just trying to milk the market before the upgrade. It leaves a bad taste in my mouth, so I won't be getting this product again.