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I’ve installed Vista SP1 on 2 machines now. My home machine and my laptop. Installation on the home machine was straightforward although it did take 50 minutes. You are warned before the install it could take an hour or more so this isn’t a trivial upgrade your customers can do in 5 mins.
On the laptop I got an installation failure due to an unsupported language:
The fix for this can be found in the following Microsoft KB article: