Sure, you could but then you'd loose many database benefits (i.e. transactions). You have plenty of different approaches to queries: "manual" for loops, LINQ to XML, XPath etc.
There are several free in-process, copy and paste deployment (no separate installation) databases out there. I consider them as a better approach (you can upgrade to a serious database if necessary, they provide obvious database benefits, etc.). One of them is
Sql Server 3.5 Compact but there are others as well.