In order to install steam games on a Mac without Windows, you'll to download the Crossover application. After you have the Crossover software, place the CD in your hard drive. Click on "Install Unsupported Software, after you highlight it in the list. Click "continue". Rename the bottle. Click on create. Click continue. Follow the install wizard through, accepting the terms and clicking "next". Register your product ID, if you haven't already done so. You may have to force the installation. You will need to re-boot, in that case. When you get a popup, you can choose the game that you want to install and click "install". When they are installed, just click and launch it. Crossover is available at their website.
Oh... and if you're working from home these days, be sure to check out Gadget Hacks' Working-From-Home Essentials.