Sharepoint V1 no. All of the pieces that make up SPS v1 must reside on
the same machine (Search, WSS, Portal ect). V2 does allow you to create
server farms and place different software servers on different hardware
servers.

Then what is the best way to deploy Sharepoint securely as a extranet?

Since it cannot have a separate  iis server  in a more secure dmz, you have to
open holes to your internal network for it to function as an intranet and
extranet don't you?

I have never set up SPS as an extranet server  so others out there can
jump in and supply better info. We have not pushed or used  SPS as
extranet solution for 2 main reasons, first it seems to take a lot of
tweeking to get running, second you can not separate  the front end from
the data which is your issue. My company does not feel to good about
placing client data outside the firewall.

Now v2 which is in beta right now has the ability to place the data on a
separate server.

I support  customers working at client sites. Since they are behind a client
firewall, they cannot VPN. The extranet  solution seemed great, but not
practical without a secure method such as a second server.

Hopefully, V2 will be released shortly.