I usually use my 360 for gaming, because my computer is crappy.
I said it once I will say it agian. You do all your gaming on the 360. Do you plan on doing your gaming on the PC?
As usual alot of miss facts about PC is better. It doesn't matter if the PC is better, the question is what is better for you? A Ferrari is better than alot of cars, not everyone has a Ferrari though. So do you really need it?
Yes PC has better graphics. Graphics isn't everything espically since they screens they took are from the 360 look great to awsome from what we see in the pics.
Yes the PC can use mods. Mods are overhyped. Are you playing TES games for the game or for mods? Arean had no mods, had a blast. Daggerfall has no mods, or that I am aware of and I have had a blast playing that. Morrowind had mods, I played over 300 hours on the xbox. Same for Oblivon. Years later when you get a better computer, like I did, then you can but the game on PC and then play with mods. You appreciate the mods better years later.
Also the 360 may or may not get DLC first. So there the 360 has something over the PC.
Also yes you can buy a cheap computer to play Skyrim for $400 if you are lucky, BUT you will not be playing games next year for it, so no Crysis 3 for example. So your Skyrim playing computer still svcks.
Yes the PC will play faster, maybe even smoother if you have a computer that will play it great. But is it really worth the $400?
Will you even be able to build yourself an awsome or good computer cheap?
So how much do you want to spend for Skyrim? $60 or $400+?
For me, $400+ in my case it would be $1000+ where I live and I don't know and have the patience to build a computer is it's not worth it for mods, or better resulution or faster load times.
I am perfectly happy with the 360 and it's old technology.