You did not specifically mention your UAC configuration and user type... you should leave UAC enabled, create a second Administrator user with at least a simple

You did not specifically mention your UAC configuration and user type... you should leave UAC enabled, create a second Administrator user with at least a simple password, and downgrade your normal account to a regular user. (This is all for a home version of Windows, the business versions offer more configuration options.) Any unexpected popup requiring the administrative user's password is usually enough to know something bad is about to happen... and if software doesn't require Administrative rights to install it is usually either easy to remove or exploiting Windows in a way that's unavoidable once it's hit the machine.