You can always run some older games with an emulater on the Wii. Of course you should only do this with games you already own on cartridge.

As soon as you start getting into old games however you will find that a good percentage of the quality comes from the nostalgia factor and is something completely mental. Once you play the game it won't live up to your memories. At least that was the case for me with such classics as River Raid, Pole Position, Conan, Zorro, Spelunker, etc. I used to play on the C64 and early arcade machines. Some games just require the context of the time period they're released/played in. Those memories add as much to the game as its code and graphics.