I have just updated my 2g iPhone from 2.0 to 2.0.1 :hack:, it's work look like a charm, very fast and smooth.
The instruction as following :
1. Upgrade iTune to 7.7.1
2. Download the iphone 2g firmware 2.0.1
3. Then ALT+click (osx) or shift+click on "update" (NOT RESTORE) and select the manually downloaded iphone 2g firmware 2.0.1.
4. Let itunes update your iphone.
5. Good luck with iPhone 2.0.1 .