Checking file integrity please wait
So first time this shows up I wait ... after all I waited so long to be able to play this game again and on Vista (goes for pretty much any game I've got here) ...
The check is done, Vista prompts me to allow the install and guess what? I has to check it again :s
Oh well I started skipping it after wards (that was until my Painkiller got a case of the munchies after installed it and decided not to run, now I wait once more)
So I was wondering what are the rest of the community's feelings on this, if any.
(Yes, I used the search function so it this as already been discussed I am sorry but I couldn't find it)

I only get a single file integrity check when the installation first launches on Windows XP. Maybe your double check is a Vista thing?

Vista sucks. That's the most direct I can make it. I might be wrong, but I'm pretty sure that you can stop Vista from checking the integrity, morality, intelligence, etc. of the file. I think that Windows 7 will get rid of most of the problems, disabling the background services, etc.

I've no issues with it, but it takes only a minute or so on my XP SP3 rig. I wonder if all Vista users are having similar issues to yours.

I've always wondered about it. It seems somewhat superfluous to check the file integrity twice in a row, but the games I've bought so far have been small enough that it hasn't taken very long, so I've never bothered asking about it. However, I'm thinking of getting Painkiller one of these days, and a double integrity check on a file that size should take quite a while. I'm not particularly looking forward to that, I must admit.
[EDIT] I'm using Vista too.
While it does appear to be an issue only on Vista machines, it's not Vista itself that's doing the checking, it's the GOG installer. Their distinctive graphic style makes it quite easy to tell the difference.

There's nothing wrong with vista, it's a good OS, it's done everything I've asked of it. Maybe x64 Ultimate is the good one and all the others are crap?
Also, I only get a single integrity check when installing GOG stuff

I am using 64-bit Vista, and the only reason why they have not as many problems is that no third-party company is allowed to get into the kernel, unlike 32-bit. Not sure if that means that GOG is fine, I wouldn't understand why GOG would want to get into a kernel anyway.

The check itself doesn't take too long (still can't play the game for some reason though) and you can always press the skip button. That is what I did the first time I installed it.

Never had any problems with the GOG installer in 32Bit Vista Ultimate.
And as Wishbone said, the file integrity check is not something Vista does, and since there apparently is some with problems, and others without, it's probably not a problem with the OS. It seems more like the PEBKAC.

Most IT problems are in the end...

I like how you agree with my technical evaluation, and then lumps me in with the clueless users afterwards :-D
However, since I do have the problem and I'm not doing anything out of the ordinary when installing GOG games (I even install them to the default folder), I don't think PEBKAC applies. It's obviously not directly caused by Vista, since some Vista users don't have the problem, but that doesn't mean it's caused by user stupidity. I can't imagine any way I could manually trigger an extra integrity check during installation anyway.
Speaking of PEBKAC though, some may be interested to know that the Danish equivalent is "Error 40", meaning that "The problem originated about 40 cm in front of the monitor."

Even most of my own problems are caused by myself, so I'm not saying that I'm perfect or anything, but it's more likely to be the users fault, whether it's because of an oversight or ignorance, than anything else.
I had problems with Arx Fatalis and MDK2 for some unknown reason, which I only managed to fix by reformatting the computer, and that problem was probably caused be myself.
To say it differently; no matter how much, or how little, you know, you will always screw up. Whether you are a hardcore IT-expert or a noob with little to no experience with computers.
The benefit of being the former though, is that you might often fix it yourself.

Well I've had the installer take a fairly long time to start and have assumed I didn't double click fast enough and so did it again only to be presented with 2 installers but that was fairly obviously me being impatient
And the detriment of being the former is having the latter come crying to you every time they break their computer because "Me email said I won a free Wii!"

Although I am very likely to make mistakes on my computer (I often enough do) I have a bit of a hard time believing that the double check is an issue of mine ...
Especially since more users seem to have it :s ... It is very easy to go around just by skipping it, but just because you don't share the same problem does not mean it is user originated.
About the noob or hardcore computer dude, I hate when people assume I know a lot about computers just because I play on games on them :p
My favorite so far was 3 days ago when 2 girls asked me to fix their internet connection :D I was actually able to fix it by reading the installation manual (it was in dutch and they didn't speak dutch). Nonetheless, they assumed I was some sort of technician because they saw me play an online game at Uni :D:D:D:D:D

well lets hope that windows 7 will solve this prob theres security then there's pointlessness