A. When you attempt to execute a file with an unknown file extension in Windows XP, the OS connects to the Web and recommends programs you can use to open that particular file type. If you want to manually determine which programs you can use to execute specific file types, visit the following URL:

http://shell.windows.com/fileassoc/0409/xml/redir.asp?Ext=<extension to check for>

For example, to determine which programs are recommended for opening .doc files, visit the following URL:

http://shell.windows.com/fileassoc/0409/xml/redir.asp?Ext=doc

For a comprehensive list of file extensions, visit the following URL:

http://filext.com