To disable the generation of short names, go to regedit and set
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/FileSystem/NtfsDisable8dot3NameCreation
to 1.
This and similar registry keys are found in Windows XP, Vista, 2003, and perhaps other versions of Windows that use NTFS.
Setting the key doesn't eliminate existing short names, but it does stop new ones from being created.
You'll have to reboot for the changes to take effect.