In the "standard" format over there (called "open"), all cards are legal. Star Wars CCG is a game that has never banned a card, and the Player's Committee plans on keeping it that way.
That being said, there are events where Episode I cards (among others) are not allowed, in a format known as Worlds 2000. In this format, you can use cards up through Death Star II.
If you want to learn more, head over to starwarsccg.org and sign up for a forum account. There are some major changes going on right now, so some of the people (Brad Eier, James Paul Booker, Brian Fred/retwin, Blake Huffman/anodos, etc) are a little riled up and intent on causing problems for everyone else. The truth of the matter is that the PC does have the best interests of the players in mind, both current and returning.
The best way to get into the game is to buy lots on eBay - there are probably some people getting out of the game right now, so hopefully you can get a good collection on the cheap.
That's all I have time for right now, I'll keep up with this thread though.