Can a system builder sell an OEM copy of Windows Vista without attaching it to a peice hardware?

YES! YES! YES you can!!!!!!!  As long as you do not open the package AND the end user is assembling their own PC (at that point the user is considered a system builder).  As of August 2005, the licensing changed on all of the OEM licensing packs—1, 3, and 30.

 

If you open the pack, you must preinstall. If you are planning to preinstall OEM software onto new machines,
  • buy in the correct denominations (1, 3, or 30)
  • open the packs and
  • distribute the individual software licenses preinstalled on the new machines you are building.
If you don’t open the pack, you can redistribute to other system builders without any hardware. If you are planning to distribute software only to other system builders,
  • buy in the correct denomination (1, 3, or 30)
  • don’t open the pack, and
  • redistribute unopened packs to other system builders without any hardware.
OEM system builder software packs are intended for PC and server manufacturers or assemblers ONLY. They are not intended for distribution to end users. Unless the end user is actually assembling his/her own PC, in which case, that end user is considered a system builder as well.

For more details go here: 

https://oem.microsoft.com/script/contentPage.aspx?pageid=555857