I'll be playing it on the PS3. TES stopped pretending to be designed with a PC in mind with Oblivion, so aside from mods (which I've never been a fan of anyway), I don't really think there's much of a benefit beefing up my PC to play it.
That is, of course, when I eventually pick it up. I'll probably wait until 2012 when it comes down in price. I never thought Oblivion was all that great, so I'm not really expecting to be blown away by Skyrim. My main interest in it is the engine, as Fallout 4 (and, if we are lucky, a superior Obsidian developed Fallout game) will be running on it, and that's the only franchise I'm remotely fanboyish about.