Yes, but it's not all that simple using Windows-only utilities. Ordinarily, you can use a version of Internet Security such as Norton Security Deluxe, or McAfee SafeScan to do this rather easily. There are also standalone products from both of these companies and others offering "personal firewall" products which will do the same thing. And there are various 3rd party utilities that offer that same feature; some are free and some are paid.
Any particular reason why you wish to Block all outbound traffic?? As Pat suggests, if you attempt to Block all outbound traffic on your computer with Windows or any other program, you can pretty much kiss goodbye ever using the Internet again until you re-enable your outbound...