So way back when Oblivion hit the shelves I didn't have a new system. In fact, I had to turn most everything down just to keep fps reasonable when outside. Thankfully I just put together a new system Apr last year that will hopefully render Skyrim in all it's greatness.
What was your system specs then & now?

Then/Oblivion:
Intel P4D 2.6
2 gigs of 800 Mhz ram
GeForce Ti 4400 (AGP)
Soundblaster Live
Win Xp Pro 32bit

Now:
EVGA X58 SLI SE
I7 920
6 gigs of Trip Channel 1600 Mhz ram
2x GTX285 oc (by Nov upgrade to 4 or 5 series dx11)
Soundblaster XFI
Win 7 64 bit Home