You are better off using the DHCP on your server rather than the appliance to take advantage of the more robust features and options that the "box" will not do... Passing paramaters such as the DNS server, WINS server, WINS options, default gateway, domain name, etc. etc. etc. etc... is not always available from the box. We even use the reservation feature to fix the IP addresses of our printers (makes tracking the printer IP's easier). The DHCP also gives you a listing of IP addresses it has assigned and to what computer (won't get that from a box). For now, you are up and running, but consider switching to the server DHCP sometime in the future.
BTW: If you should only list your internal DNS servers in the option. If you can't reach the internet, then you need to delete the root zone on your DNS server and configure a forward to the ISP's DNS server from yours (lets your DNS query the internet DNS to resolver internet name addresses).
Start, Help. You'll be surprised what's there. A+/MCP/MCSE/MCDBA