First of all, let me tell you what I have.
I have a residential broadband ADSL connection with a static IP. Download is 15 Mb/s and upload around 800Kb/s.
My home future server is just a laptop. 1,6 GHz, 2 GB DDR2 RAM, XP Pro SP3. Generally speaking, I use Joomla to build sites. I plan to have a web site hosted at home and also have a SMTP server to manage e-mail.

I have a domain name and I want to make sure that I did everything right with DNS configuration.
The web site that manages DNS has the following fields:

1) In A record there's a SUBDOMAIN box where I just put @ sign (it means root, right?), then there's a default TTL 7200, and IP ADDRESS when I put my static IP.

2) The next line is CNAME record and in SUBDOMAIN box I put www and then 7200 TTL and then the HOST NAME where I just typed mydomain.com

3) The next line is A record for a mail server. In SUBDOMAIN box I have smtp, then TTL 7200 and finally IP ADDRESS.

4) And the last line is MX record. In SUBDOMAIN I have smtp, then TTL 7200 and then PREFERENCE 1 and the last thing is HOST where I have my domain.com
Are those parameters correct?

I plan to use Ubuntu Linux NON Server OS with Apache on it (probably LAMP) and for SMTP Server I'm not sure...I found Citadel. I used to have hMail couple of years ago and I really liked it, but it works on Windows only.
Frankly, I don't like Linux, but I think that in my situation its the best bet. One thing is not clear to me though...Why would someone use a command line Server Ubuntu Linux when there's a GUI version of Ubuntu that runs Apache as well?