Don’t. It’ll brick your phone. You might want to wait a bit, as other flutherers might also tell you.

Um. I installed the 2.0 update on my first gen iPhone and it doesn’t crash, at all.

My iPhone 3G doesn’t crash either. Both running 2.0.

Mines been fine with the 2.0 update, too. I downloaded it before it was officially released as well (maybe that has something to do with it?).

were can I get it?

Follow the guide here. Even though it’s aimed at people who upgraded early, if the normal iTunes upgrade isn’t working for you, you should end up on the official 2.0 firmware.

Downloading the software isn’t the problem. It’s reactivating your phone. Because the upgrade is a full numeric one, it has to completely wipe your phone and reinstall the OS, as well as reactivate it. This is why they’re making such a big deal about backing your phone up, because it will be erased. My point is that actually getting the install is not a problem, it’s reactivating your phone through itunes.

Patience is a virtue. It may work fine, but there’s a chance you’ll be without a phone for a while.