I think that's a good way to describe my problem?

I have a datagrid on my webpage that is bound to a typed dataset. Each time I add a row to the dataset, it adds to the datagrid. The problem is, the next time I add a row to the dataset; the original is gone and the new one is in it's place.

I (now) realize there isn't viewstates with datasets and I need to store the values somewhere between page refreshes. Since this is a dataset that needs to be filled before the page is submitted, I would like to have an intermediary xml file I could populate each time a new row is added and only talk to my database twice (once for page load, once for page submit).

The problem is, I can't figure this out. I would like to make a hardcoded xml document that can temporarily store the items until the page is submitted, but can't find a decent resource. Most of them are for permanant data store and not on a "per user/per page" basis.

I won't put this on your shoulders to explain all this to me. It's too much and I'll probably have quite a few problems. All I'm asking for is a good resource that exaplains how to make XML templates and use them for temporary data storing.