to have made the giants move, as both AMD and Nvidia has released new Beta graphics drivers on the same day, something that doesn't happen too often. In all honesty, AMD is calling theirs a hotfix and not a Beta driver, but it's all the same to us.
There's a reason why AMD is calling it a hotfix though, as the following can be found on AMD's website: "737-29041: BioShock: Users may experience stuttering with Preload, Missing surfaces and/or display corruption."
Nvidia on the other hand only lists "Improved compatibility for Bioshock." which doesn't give away too much at all. Interestingly the same Beta drivers also adds this "Added PureVideo™ HD decode acceleration for GeForce 8600, 8500 and 8400 series GPUs" so it looks like it might be worth downloading even if you're not playing BioShock and have one of those cards.
You can download the AMD driver here and the Nvidia one here for both Windows XP and Windows Vista 32/64-bit. Please note that the AMD driver is close to 100MB and we're not quite sure why it's that big.