I've never gotten steam to work properly with any application virtualization solution. I've tried VMware Thinapp, Turbo.net, Cameyo, PortableApps.com. Nothing is perfect. The closest I can get is Turbo.net, however special mentions should be given to PortableApps.com. If you have the time to properly configure it, you can virtualize any app and is extremely stable and reliable. Only problem is it is not dynamic like the other 3 are and you have to manually set the files/directories/registry keys to virtualize. If you are just looking for a simple solution, then give Turbo.net a try. If you are a more technical user and don't mind to manually configure it, then give PortableApps.com a go. If you need help with either, let me know.