max size to store data in an xml file

Question

I'm using a file XML in my ASP.NET project to store information (entered by admin only). I would like to know the maximum size of an xml file is allowed in a project?. (size can be measured in number of lines, GB,etc.).
Also, My xml file must be updated programatically by adding new lines.
 
Also suggest me, 
Actually, some data by admin would be updated and admin want to list of name and description of members of a company, so,members would be add, update or delete. Would this member information too store in XML? Would never issue of space came in future?
IS using of XML file good?
 
Note: as already told only admin would going to store information. i.e. user (client) would be only able to see the updates in website.