and would you therefore consider this spec good
Windows 7 Home Premium
Intel i5 2500k Quad Core
4GB Samsung RAM DDR3
NVIDIA 1.25GB GTX 570
2X 1TB WD Caviar Black Hard Drives
.... I know what I think but for others as a reference would they need something better or not even as good... I will be getting it on PC, me thinks..... Simples
As you're running Windows 7 and not Vista, that is enough RAM - Skyrim (like most games) shouldn't use more than 2GB of RAM, and your OS will use another 1GB, so you will have enough to spare there. An i5 quad core proccessor will be more than enough to run it - most good dual cores would run it on medium settings, so a medium/high range quad core will rip it up. You 1.25 GB graphics card (and the fact it is a GTX 570) will definetly be good enough, and your 2TB of HDD space is most definetly enough.
@The OP, don't get the XBOX version. Sure, at the moment your PC and the 360 version will look similar. BUT, when you get a better PC (even if it is in 3 or 4 years time) then it will be able to run it looking better, and most importantly
YOU CAN GET MODS ! There is a huge wealth of mods for Oblivion on the PC - one of the reasons it's one of the best games of all time. They add SO much more content than just the original game, it is most definetly worth it.