How many games I have in my steam library: 100+
How many games in my steam library that has already been ported to Linux (as of yesterday): 6
I will make the switch when they have at least 1/3 of my steam library ported over to Linux.
Give it a few years though; I think there'll be a slow trickle of games for a while, but it'll start to ramp up as some of the bigger studios realise there's a market there.
Just for rough specs; both my Windows 7 64-bit & Ubuntu 12.04 64-bit installs have their own SSD (Samsung 830), on an i5 2500k/8GB RAM/nVidia 560TI machine. TF2 is installed on both the SSDs.
Sadly, there still are a few dealbreaker apps that prevent me to switching to Linux.
There's also the massive back catalogue Windows has, my girlfriend loves playing random PopCap games and other casual-friendly stuff that are not yet click-and-play in Linux - was going to say "not available" but Google has an installation guide for Wine, but not yet available to mainstream users.
I expect they'll probably arrive soon, since all the Humble Bundles have been Linux-friendly for ages, but they don't have the games available now. They're probably trying to get the client more stable, I guess.
Seeing mainstream support (Steam and others), and 62 titles shows Linux has gone a long way, and of course the rise of web gaming is a huge boon.
Just not on Linux Steam, yet.
Probably still the best games on Linux imho...
I don't like First Person Shooters (even the original Wolfenstein gave me motion sickness, and I don't have great motor skills), that's why I forgot about those.
I've always liked turn-based strategy games, or real time strategy games (at medium or slow speeds, I get destroyed on online matches), puzzle games, point-and-click graphic adventure games, etc... and I distinctly remember searching for those and not finding much back then.
I definitely need to give Linux another try, but I don't manage to convince myself to set aside the time (it might be a good investment, though :) )
Sid Meier's Alpha Centauri is a favourite of mine, not sure how easy it is to get a copy of these days though.
DEFCON, Darwinia: http://introversion.co.uk/
Wesnoth is a great turn-based strategy game and has an unusual amount of polish for a FOSS game.
SpringRTS is a really fun RTS, if you can look past the many bugs in the launcher/lobby: http://springrts.com/
As a mac user, I don't see a good reason to get a Linux box for steam as most the Linux games are also for OSX. This is important to me as I am completely open to the next generation of consoles. Nintendo is automatically out but I have been considering going back to windows if the next generation of playstation and Xbox do not excite me. If the Linux steam catalog was at least in the ball park of the windows catalog I would consider it.