If you're buying Oregon Trail from The Learning Company, get Oregon Trail II.  This is the definitive version of the game, and despite being over 20 years old, it's still a lot of fun and entirely playable, which cannot be said for later editions, especially the utterly broken 5th Edition that somehow managed to get a major release a few years back.  If you can find a working copy of this game (this is a newer release which worked with XP), it's highly recommended...otherwise, avoid the later editions and seek your Oregon Trail fix elsewhere.