You guys use several uncommon directories for 3rd party components : 1: windows\System32 for some BPL
2: Delphi\Lib for some dcp
3: Delphi\Bin for some other BPL
4: UniDAC for dcu

How about using
BDSCommon\BPL for all bpl
BDSCommon\DCP for all dcp
leaving the dcu in the lib of the unidac install directory

To explain : As a developer i work with several virtual PCs that I have to update. I use a local SVN for that. Installing unidac is always a hassle because after the install I first have to copy everything where it's supposed to be and then i can update the svn and update the VMs when needed from there.
It would also go nicely with fresh installs, I just keep my user directory and my data hard drive with my source and component installs. If I leave the component stuff where it is after the install, i'd loose all related to unidac