Use the Nexus for modding Oblivion I think, same as Skyrim (it's mandatory for some people on Skyrim now. The workshop has been partially or totally broken for Skyrim since Steam went through that whole paid mods thing).
Almost forgot, but I picked up Age of Kings HD while it was on sale, so I'll be enjoying that later. Anyone else who was looking at that, it's 80% off for the next 8 hours still. I do hope the game is half as fantastic as I remember. Age of Kings and Star Trek Armada, those are the RTS games I really like. Wonder if I could get Armada working actually. The Star Trek vs Star Wars mod deserves to be played again...
Anyway, will be enjoying Age of Kings later.
On a side note, apparently right now the patch for the expansions is pretty broken. Some bugs like idle villager button not working and a lot of crashes. So maybe buy it now and wait for fixes before trying it out