Since about MS-DOS 6, a folder (or directory) is "just another file" to DOS
and Windows. Therefore, we can keep creating folders and expanding them
indefinitely (almost) until we run out of disk space. For the official
version of the limits, see the online version of the WinXP Pro Resource Kit:
Size Limitations in NTFS and FAT File Systems http://www.microsoft.com/TechNet/prodtechnol/winxppro/reskit/prkc_fil_tdrn.asp?frame=true
There ARE limits, but they are so high that we are not likely to hit them
for a year or two. ;^}