OK...
My wife and I both have the i760s...
I decided to try the upgrade on mine first.
I did this on my XP SP2 PC.
I found that I had to run it twice... the first one gets the PDA updates.. the second time gets the phone upgraded.
I then read all the issues all you have had... was scared to try my wife's...
But, oh well, dam the torpedoes... go for it!
I updated hers on her XP sp2 Laptop.
The upgrade was identical... the first try upgraded the PDA, it quit with that Open something error.
Then the second try gets by that and finishes the phone upgrade.
Now both are upgraded!!
I haven't had any problems with Wifi, Active sync, or any of the other things that seem others of had problems with.
I think the moral of the story is... the XP version of the upgrade seems to work good.
Hope others are getting through with theirs now.
Paul G