And now, thanks to this week's Humble Star Wars Bundle, you can get almost all of the good Star Wars games at the same time and on the cheap.
There are a few noteworthy exceptions--no Tie Fighter or X-Wing, nor do you get the first two Jedi Knight games--but all in all this is a solid package. The "Pay Anything" tier includes Knights of the Old Republic, Jedi Knight: Jedi Academy, and Dark Forces.
Pay more than the average and you'll also get Republic Commando, Knights of the Old Republic II, and Battlefront II. Some of the games have aged better than others, but I'd say every single one of these games is a classic.
Things get a bit dicier in the "Pay $12 or More" tier, with Force Unleashed, Force Unleashed II, and Empire at War. Empire at War is the strongest of the three, but I wouldn't say any of them are must-play games. They are the most recent releases though, so probably the most approachable.
Note: This is a full-on two-week Humble Bundle, so there's a chance more games get added next week for those who paid more than the average. I'd guess Jedi Knight II: Jedi Outcast is probably a safe bet, at the very least.