File/Folder names cannot be created in Windows XP/Vista

In Windows XP/Vista, we cannot create file/folder with the following names:

con, aux, nul, prn, lpt(1-n), com(1-n)

The reason: those words are reserved as MSDOS device drivers
Source: http://support.microsoft.com/kb/74496/en-us

But, if you still INSIST to have folder with those names, here is what to do
Source: http://kerneltrap.org/node/5772

Run in Command Prompt (Start - Run - cmd)

To create folder aux in drive D: mkdir D:\aux\
To remove folder aux in drive D: rmdir D:\aux\
To copy file into folder aux: copy filename.ext D:\aux\
To delete file in folder aux: del D:\aux\filename.ext

Note: you cannot copy files to or delete folder manually in Windows Explorer

Also, if we already have a file named "test" in a directory, then we cannot create a folder named "test" inside that directory, and vice-versa, if we already have a folder named "test", we cannot create a file named "test" in the same directory. In this case, we cannot trick it even using Command Prompt.