service component is necessary, as it has a lot of features which require more than UAC gives to you by default. It basically runs a service at elevated permissions, and communicates with the Steam client, doing things for it that normally would require Administrator access. For the second option, you would run msconfig from the run menu (Windows Key+R if you're using the default Start Menu, as Run isn't there), and look for this option . Click "Launch" when you have it selected, then reboot. The shame (and I've brought this up before) is that you still have to install the Steam service component (you can actually choose not to and Steam will run fine, but it'll just prompt you every time you launch Steam) due to the fact that Steam doesn't detect whether UAC is on or off. The resource usage isn't substantially higher, with mine sitting at 2.7MB memory usage and no CPU usage constantly, but it's just annoying to see it there. The upside to disabling UAC is there are a lot of applications that aren't UAC aware that won't bother prompting you, and they'll fail for what looks like no reason, and it just adds to the hassle of using them, as well as the fact that you won't have to be prompted every 10 seconds to see if you really want to run something. In 9x, there was no concept of administrators and standard users and the like, everything on your computer ran with full