It's great that you're still involved with your chapter!
The nationals template is very easy, and in some cases too broad, but none the less is a great easy way to create a chapter website. To create your chapter website go to
http://www.chiomega.com/siteCreator/
You do just enter your chapter's information into their template and there is nothing more you really have to do. I would suggest that since you already have webpages through geocities you link those off of the national template, that way you can save what you've already done and make your page more interesting.
I did just that with our chapter website with the nationals template. Here is the link (Pi Zeta Chapter at Western Michigan University)...
http://www.chiomega.com/pizeta
Hope this helped!
Lauren