To DNS serve, or not to

[agent dero]

I am setting up a home based server, that will host a couple domain names
on 768k SDSL. I have the server all lined up and I am wondering what I
should do about DNS serving. I figure I have three choices.
a) install BIND on my web/ftp/lan server (also doubling as network firewall)
b) get an old junk box, like 300Mhz w/ 64MB RAM and use it as the DNS Server.
c) use a free off-location service, such as zoneedit.com to handle DNS
requests, that come to my static IP.

With option (a) the server is a dual CPU, high powered workhorse, but I am
worried about the security, and managability of putting all those features
in a single box.

agent dero