You have several different options to choose from. Normally you'd want to run
your portals on port 80, which is the default port for HTTP. To run two sites on
the same port on the same physical server you need to use different
IP-addresses, or you need to configure host headers. The easier approach is to
use different IP's:

- Add new IP-address for the server (from Network Connections > TCP/IP >
Advanced > IP). If you currently have an IP of 192.168.0.5, you can add
192.168.0.6. Check with your network administrator that this is okay though!

- Start IIS Manager (Start > Run > inetmgr), select portal which is running on
port :200 and open properties. Select from the first page 'All unassigned' to a
specific IP-address. Set the port number to 80

- Select the portal running on port :300 and open properties. Select the
secondary IP, and set the port number to 80.

Keep in mind that you are still using the same physical network card -
performance may become an issue later if your server gets lots of requests.
Also, check that your DNS-server is configured properly so that your new IP's
are mapped to meaningful hostnames with correct domain names. I.e. 192.168.0.5
is mapped to foods, and 192.168.0.6 to beverages. Port numbers are still
configured via IIS.