So yeah, I own Steam's GotY edition for Oblivion (Picked it up for a song on one of the multitude of sales awhile back). I just installed the game, feeling the "itch" again...but each time I go to start it up, it immediately crashes to desktop.

Is this a known issue with the Steam version of Oblivion? I have a hard disk copy of Oblivion's GotY that I know has run on my rig before (Yes. I own multiple copies. I also own a copy for the Xbox 360. I'm ill.), so I do have options to get the game running if needed. I'm assuming at this point I'll need to.

I gather that you uninstalled the GoTY version at some point. Did you delete the Oblivion.ini in My Documents\My Games...? If there's an INI there from a previous install, it will cause the game to bomb out. You need to remove it, to let the game create a new one.