C:\Documents and Settings\
'Your User Name'\Application Data\cYo\ComicRack
Now this is the default location on XP/2K machines to store application specific, network roaming data. By default the Application Data Path is hidden, so you may have to change the settings in your explorer or type the location into the explorer address bar to get there.
In there is ComicDb.xml, the comic database. It's a quite simple formatted xml file. I will post the schema format someday.
But ComicRack also stores Meta Information directly into the comic files (cbr/cbz/pdf etc). So even if you should delete your database or remove files from it, when you re-add them, the info is there again.
BTW, it is already possible to store the Meta information into a separate xml file with the
File->Save Book as...
Command. Just select the proper format in the Save Dialog, right there after the formats to save your comic as a PDF-file or a list of images.
So the main point is: Data entered for your comics is not stored in some special format you do not know and is lost if you wanna change your software. There is no vendor lock in :)
So going to sleep now and catching up with she-hulk (the comic i mean :>)