You're video card would certainly chug on oblivion on high settings, but your rig should be able to hand anything last year or older on at least minimum settings.
My guesses on quality
Counter Strike: High
Minecraft: High (duh)
COD 4: medium
Oblivion: medium
Fallout 3: low-medium
Fallout New Vegas: Low (not optimized as well)
Newer games like the witcher 2 are far out of your reach currently. No you can't upgrade your graphics card, most laptops don't have the architecture for discrete (read: external) graphics cards. If you feel yours games run too slow, your only options are to get a new machine or get more RAM -- I would recommend the former.
My guesses on quality
Counter Strike: High
Minecraft: High (duh)
COD 4: medium
Oblivion: medium
Fallout 3: low-medium
Fallout New Vegas: Low (not optimized as well)
Newer games like the witcher 2 are far out of your reach currently. No you can't upgrade your graphics card, most laptops don't have the architecture for discrete (read: external) graphics cards. If you feel yours games run too slow, your only options are to get a new machine or get more RAM -- I would recommend the former.