where is the pagefile at?

You mean "where are the pagefile settings?" Knowing where the actual pagefile is isn't going to help you.

Depends on which version of Windows you're running. Usually, right-click on "My Computer" and select "Properties". On Windows XP, under "Advanced" click on "Performance" / "Settings", select the "Advanced" tab, and then hit the "Change" button.

Usually you won't want to do this, however, because Windows generally (at least these days) picks the right settings for you.

More likely is that your DVD software's got a bug in it that causes it to eat memory, and it doesn't matter how much virtual memory you configure -- it'll still fail.