EDIT: if you are thinking Oblivion..there is a little difficulty bar in the menu options that lets you raise how difficult everyone is to fight. So if you want a real challenge then crank it up to the top and you will have a quite the handful. and if you want to stroll around then just set it down too the lowest setting. My favorite memory of Oblivion is when I got my Agility(? Jumping) all the way up and I was able to jump from the ground to a roof top and then manage to jump out of a castle itself and break the game lol =) If not Oblivion, then you might want to try out Dragon Age origins. It keeps you pretty busy and the story line is great aswell with the leveling up stuff. Fable is always an easy one to sink your teeth into...and you can buy the original Fable on games on demand. Brutal Legend is a pretty neat game too, you may want to only rent it though because gameplay is starting to get kind of repetitive for me. Oblivion Fable I, II Dragon Age Brutal Legend?
If your computer can handle it get oblivion for your PC, it has hundreds of hours of extra user created content and is generally more fun what with the construction kit and all I used to have it for the PC and I had a mod that allowed you to play online with other people and had lots of extra races, armour, weapons and buildings/cities (someone has actually re-created part of morrowind and imported it into oblivion!)
Oh yeah, easily. Get it for the PC and then get good with all of the cool stuff built into the game, then learn the PC commands, then get the TES construction set and dl custom content and ****. Its the best ever.
Just get GOTY edition, don't bother with the long downloads and the only other downloadable content isn't really worth it. Shivering Isles is almost an entire game itself, almost. Combine that with Knights of the Nine and you can't possibly be bored until well into next year.
That isn't necessarily true, I'll admit some of it isn't vary true but they new player homes and marhunes razor are worth it, fair enough the dagger form marhunes razor isn't very good but doing the dungeon is really fun and will ad an extra hour or so of play time.