There seem to be quite a few people from Austria browsing here - so, here's another one posting!
First: I have no machines running Windows, so I tried making Audiosurf work with Wine under Ubuntu Linux 8.04 (the [current] development version).
It almost works to perfect to be true. The only thing bugging me is the splash screen which is drawn completely wrong:

You have to look around with your mouse to find the selection for "Play" (it's somewhere in the middle).
The *.wmv videos in the tutorials don't work either. But that is to be expected when you use a vendor-specific codec for these.
After that, everything seems to work as expected:

If the splash screen / the videos would get fixed to work as expected too, you could claim compatibilty with Linux through Wine!
Without further ado, my answers:
-Did the auto-updater finish successfully?
Yes. No problem here.
-Does it play smoothly at the settings it defaults to or did it ask you to
decrease graphic settings?
No, it didn't ask me to do anything with the settings.
-Do the tabs on the highscore board or song selector ever get garbled
graphically? If so, what video card do you have?
Nope, only on some screenshots.
01:00.0 VGA compatible controller: nVidia Corporation G72M [GeForce Go 7400] (rev a1)
-Now that you know how to play and score points, what do you wish the
tutorial had made more clear?
No, it's fine.
Your opinion:
-What did you like about the game?
It's extremely fascinating to watch the scenery and see how to music is visualized. It's also extremely fun to have songs which go real slow for a couple of seconds and starting rocking afterwards. I love the ship's reaction to these parts.
-What did you dislike about the game?
It's too fast at times. Maybe I'm not a pro gamer, but at high speeds I have difficulty keeping track of the collector's columns and the ship (and maybe half an eye ahead to see the next few chunks).
I want more loops. I had only one or two songs where the track bent into loop. I'd also like to see big loops like in a rollercoaster.
-What was your favorite character to play with and why?
Vegas. When you have overloaded a column and you are waiting to respawn, you can use that time to shuffle up the field and use the time out effectively. It also seems to be that easiest way to get multiple colors with decent playing conditions.
-What did you think of the difficulty of the game--was it too hard, about
right, too easy?
Too much speed at times (like I mentioned above). Otherwise than that, I see it as a challenge to get better

-On a scale of 1 to 10, how interested are you in continuing to play at this
point (1=not interested at all, 10=I'd definitely play more)
9.8
Keep it up!
stephantom
p.s. If you're interested to have your game tested with wine/Linux more intensely, just let me know. I'd be happy to help!