and No, they do have some sort of x86 64 bit drivers:
As I said before, I have had experience with them on windows vista (the chrome 400 series) and they have performed...as they should have - low performance, low power cards.
I tried obscure 3D games like 'The Path' and better knowned ones like 'Titan's Quest', 'L4D2'.
They performed as it should have, with choppy frame rates but no artifacting. Actually, L4D2 was playable, with a driver which was clearly published before the game was launched. (then again, source has been around for some time)
The limited number of reviews on these S3 cards (400 and 500 series) collaborate with this. They complain about performance, but note that there are no incompatibilities when they tested it.
Besides, there isn't much harm. It's not as I'm using one of their chipsets for my Ubuntu box. At worse, if the drivers don't work, I'll just take the card out and go back to the integrated drivers.
And the cards are cheap. I mean, hell they cost lesser than say Swiftech's MCP355 pump, just a component of amusement for WC enthusiasts.