I recommend FormMail at http://www.worldwidemart.com/scripts/formmail.shtml . This is a good script and will help you get started understanding what you will need to know to administer your server.
Personally, I like Y Form. It's a nice modification of Matt's original script. You can set one up on your server and let all your sites use it. Also all the customization is done within the form fields. It has a built in autoresponder function and can log fields to a database.
You can get it at: http://www.fyi.net/~abass/domino/misc.htm Just my personal favorite. Brian