Browser As Front-End

Hi!

I'm trying to build an app. for my parents' office. They have a small
office (5 PCs), and they currently work with a very old program that's
based on DOS. The program doesn't work well under XP, so they still use
Win 98. They had their network upgraded about a year ago. They had
Microsoft SBS 2000 installed, it includes SQL Server. I've written a
few DB's in Access before, and now I'm just learning how to use SQL.
Before I start work on their app., I have a question:

I know it's possible to create an interface that can be put on their
network and accessed via a browser. How is this done exactly?

It would be very beneficial for me, because it would mean that the new
app. would be platform independent, so that they can upgrade to XP
easily. It would also save us the cost of licensing front-end software
(e.g. Access) for each machine.

Any comments would be appreciated.

Noam Nelke, Israel.