The box that holds the receptacle will either be plastic or metal. If the box is metal, it MIGHT have a ground wire attached to it, or it might have another path to ground. There is no foolproof way to tell until after you've installed your outlet. On the other hand, if the wire that goes to the 2 prong outlet happens to have a third bare copper wire, then that should be your ground and you can connect that to your new outlet. However, this is not a guarantee of a ground either, because the ground wire has to have a complete path back to ground. If there are other outlets on the circuit and the ground wire is not connected in one of them, no ground.
At home depot and most other stores you can buy a circuit tester that plugs into the outlet and indicates using 3 lights whether the outlet is wired correctly.
If the box is not grounded and the sheathed electrical cable does not include a ground wire (both of which are very likely if the outlet is a two prong, then the only way to ground your outlets is to rewire the house. Get a bid or two from licensed electricians.
How's your main panel? Are they screw in buss fuses, or do you have a 200 amp service panel? My guess is you need a service change too.
Your other option is to replace the panel, and make some individual runs from the panel to your important outlets, like the ones that power your home theater and computer, and anything where a gfci outlet would be required.
Again, you should consider contacting an electrician. If you have to ask the question you are asking, it indicates you probably don't have the skills necessary to complete this safely.