Linus dislike of (and outburst at) NVIDIA stems from Tegra more so than their dedicated GPUs. The drivers NVIDIA provide are actually very good (I'm using their 670 package on my own 670). The nouveau open source driver is basic to say the least and causes conflicts with the dedicated drivers if you try and install those over the top of the nouveau drivers on distros like Ubuntu/Xubuntu/Kubuntu. I use a ubuntu minimal CD when installing and build from the ground up so I don't bother installing the nouveau driver. Whereas if I install from a full U/X/Kubuntu CD one of the first things I do is disable and apt-get purge the nouveau driver and install the latest dedicated. Thankfully U/X/Kubuntu make installing the latest Linux drivers very easy with, I think the program is called Jockey, that detects and installs non-free drivers.
AMD drivers have worked grand for me in the past as well. But late last year I heard that AMD where planning on dropping linux support for 2, 3 and 4 series cards. Thankfully, I have a 5670 in another machine, so support should be good for a while yet. The open source driver for newer AMD cards is much better than the open source nouveau driver for NVIDIA cards.
But none of that matters if the games you play aren't well supported under wine or are ported poorly. At the minute I play EVE under wine and it was a nightmare to get everything working. Performance is nowhere near as good as it is under Windows and there's sections of the game that won't work (like walking around station quarters when you dock). Steam would be great... if X didn't crash every time I tried to start playing TF2. There's a lot of work to be done. So I won't be "early adopting" the switch to Linux gaming on a permanent basis any time soon.
