The old ATV1's are basically a Mac mini running a stripped down version of OS X and uses the Front Row app as the GUI. The newer apple TV's have internal components like the iPhone and iPads, which run on the iOS an incompatible variant of OS X.
I have looked around and do not see any links to the 3.0.2 software anymore. I would suggest contacting Apple support as it is definitely not cool that you cannot at least bring your first Gen up to 3.0.2
Try the express lane - please post how it goes & good luck!