Yes. There are numerous ways to do it depending on your environment (sorry that I am not familiar with SBS. All of the servers that I admin are 32-bit and 64-bit Windows 2003 Server Standard or Enterprise version).
If you are using a router for your Internet connection:
Use the filtering that comes with your router. Most will allow you to block web sites by URL, host names or by key words. You can administer most routers with your browser. Just type in the IP address of your router as a URL and you will be prompted for your router login. Example:
http://192.168.1.1.
If you are using Internet Connection Sharing:
Go to the host computer that is running ICS. Open the HOSTS file on that computer. You can edit it with a text editor such as Notepad and it is found in the
C:\Windows\System32\drivers\etc folder. Add a new line starting with 127.0.0.1 for each host name that you want to block - for example:
127.0.0.1
www.pornsite.com
127.0.0.1
www.mailsite.com
127.0.0.1
www.spammer.com
Note that computers obtain IP addresses for names (DNS) in the following order: HOST file, local DNS cache, DNS server, WINS server. Since you are making limited use of the HOST file, your computers will resolve the web sites to the local loopback address (127.0.0.1) instead of finding the correct address from your ISP's DNS servers.
If you are using a Proxy Server:
I believe that there may be a scaled down version of ISA Server found on Small Business Server. Proxy servers use rules based filtering and can also employ the use of add-ins that can subscribe to lists that are used to block inappropriate content in the workplace.