Apologies for the off topic chat too, but yes I saw that, and I'm hardly even surprised! Luckily I rarely buy games through steam directly, so they don't have card details for me, but nonetheless, it's pretty bad...
Out of interest, you mentioned switching some installation paths or something so that the folders installed to aren't protected and modding utilities can have access. Can you elaborate any further? I'd hate to install this hard copy I have then find I've got to reinstall to another directory.
I have never had to do it before but heres the steam support page which details the methods https://support.steampowered.com/kb_article.php?ref=7418-YUBN-8129
Noticed when steam installs from the Skyrim DVD you do not have the option to change the installation path .. So maybe better to install steam first and get the option, then just use the product key from your DVD with the DVD in the drive - Otherwise it will be a case of using the after installation method of moving the location.
Its not a problem at the moment, but as we get utilities which will need to install in the game folder (as with Oblivion) if your game installation is in a protected folder under Windows Vista or 7, then the utilities will not work/or at least throw a fit/crash/not be able to update/access files - Next version of Wrye Bash, Nexus Mod Manager?, BOSS etc etc.
Without steam for the GOTY version of Oblivion, it was only a case of Installing the game to a new path (for instance C:\Games\Oblivion or another partition D:\Games\Oblivion\ instead of the default path of C:\Program Files\Bethesda Softworks\Oblivion\. Anything installed into Program files on Vista and 7 will be problematic. Some users opted for the easy option of disabling UAC (User Account Control), lowering their system layers of protection, and its not entirely successfull unless you know how to give yourself admin privileges over every file in there. Easier (normally) just to install the game to a location outside of Vista and 7 UAC's grasp.