Windows domains and group policy

I went to a 1-day seminar Monday on Windows 2003 Server that really opened
my eyes.

I saw what is possible from a security and management viewpoint when you PCs
are a DOMAIN instead of a WORKGROUP.

The security, software deployment, shadow copying, redirection,
Intellimirror, etc. were very interesting and all require domain.

I'm trying to formulate in my mind what this could do for us if fully
implemented and have questions.

1) Does the software deployment and security stuff work as well as
advertised?

2) How much of a pain was it going from workgroups to a domain?

3) W98 and NT cannot participate.  If we still have 4 W98 and 1 NT 4.0, what
does that do to us?  Do we still need a WINS?

4) Did you get outside help?

5) How much outside training was required?

6) Was it worth it?

The whole shebang does not appear to be for the faint of heart, but anything
to help admin cost is wonderful to me.

Thanks.