|Is X: the local drive letter assigned to your external drive or the letter you wish to use when you access it from the remote system(s)? "X" seems pretty far up the alphabet unless you assigned it yourself using the Disk Management Snap-in. You need to make sure you use the local disk letter in the "net share" command on the system that is sharing the drive.|
Then, you can use any available drive letter, "X" if you prefer, with the "net use" command on the remote system(s).
Also, I if you are not using Windows Server, the /Grant parameter is not recognized. On a Windows XP Pro workstation, you'll want to use the following version of the net share command instead:
net share "193GB ZAPP OLD STORAGE X"=x:\
where x:\ is the local drive letter assigned to your external drive.
"Everyone" will be assigned full read/write permissions by default.