I followed a howto guide over at linux-gamers.net (I think) but I found that it was rather incomplete and at times gave me wrong commands but I ended up able to get Steam installed and run Counter-Strike Source through WINE on my Ubuntu Edgy box. My specs are: 1.7ghz 512 MB ram and a Radeon 9600 64mb graphics card(using fglrx)-- all wrapped into a sexy little IBM T42. Below is the quick run through of how I did it, the full version is on my blog: http://t42buntu.blogspot.com

1. Download WINE

sudo apt-get install wine

2. Run WINE setup--

wine setup

3. Download Tahoma font and put it in your wine fonts folder:

cp Tahoma.ttf /home/USERNAME/.wine/drive_c/windows/fonts

4. Download Steam the go to the directory and install it

wine SteamInstaller.exe

(Note I just took a break to test out my CSS on Linux, and after a few trial and errors i figured it out and got onto a server and played it! So, IT WORKS!) 5.During the steam install just use all the same options/answers you would use in a windows environment-- at some point it will prompt you that it needs to install a Mozilla Gecko plugin? just say yes and it will do it's own thing.
6. When the installer finishes open up a terminal and do the following to launch steam:

cd /home/USER/.wine/drive_c/Program Files/Steam
WINEDEBUG="fixme-all" wine steam.exe

This will launch steam while hiding any outputs from wine, thus running your game faster.
7. When steam launched I couldnt type my name in the login/password boxes without first right clicking in the login field then left clicking. After this I could login as normal.
8. Now that you're ready to launch your game you will want to make sure that all other windows besides the steam "My Games" window are minimized or closed.
9. Double click "Counter Strike Source" and as soon as it says "preparing" click the x button on the steam window with "My Games List" or it will interfere with the game.
10. The game should be running fairly close to normal now, you ay be warned that you're video is wierd and that it's using software mode, but even on my 1.7 Ghz 512mb ram 64mb Radeon 9600 the game was more than playable.

I will be fidiling around with all the settings later so check the blog for updates on it.

I hope this helps someone.