Logistics for a bind-DNS newbie

[Papi]

I have a kind request for the DNS/bind gurus out there, in regards to
something I would like to try, but not sure on how to do it, without
screwing something up:

- existing setup: dual DNS setup, with a master on my premises, set up
years back on a W2K machine, which is SOA for mutiple domains registered
to us, and a secondary at the ISP, which is supposed to pull the info from
the master

- desired setup: I would like to have a two-step process, at the end of
which I would get rid of the W2K DNS. I am thinking of setting up another
bind-based DNS server (1st question - how to integrate it, w/out breaking
things) as a third one for all my domains/zones, then remove the W2K one,
while (2nd question - how?!?) making the new bind-based server take its
place in the scheme of feeding the ISP server with the info (i.e. the
provider pulling info from the new one)

I would appreciate any pointers to docs, or advice in regards to steps to
achieve the above (or if anything appears to be flawed in the logic).

Thx,
Papi