What you need to do is define a new section where the Arabic numerals are meant to start. To do this, go onto the page you want them to start, and press Alt-I, B (I'm not where it is in Office 2007, but the 2003 shortcut works), and choose "Continuous", and press OK. Then if you go to the footer on that page, you should be able to pick the "Format Page Numbers" item on the Page Number drop-down on the Design palette. Click "Start at", enter the page number you want proper numbering to start at, and press OK. It should then have separate numbering.
This page may help if you're still stuck.