Again: Samus Aran, while equipped with the Gravity Suit, isn't damaged by most lava. The people who are saying that Boba Fett could defeat Samus haven't played a Metroid game. Hell, the people who would say Darth Vader could defeat Samus have never played a Metroid game.
You could argue that Boba Fett is "cooler", but when you're looking at raw power there is no contest. Samus Aran is ridiculously powerful and basically undefeatable (assuming you are even moderately proficient at playing Metroid games).
Edit:
1.) On the lava thing: It takes a ton of energy to melt stone. A lot more than it takes to, say, vaporize water. If Samus isn't unduly affected by swimming through molten rock outside of one area, it means her suit can absorb a lot of power.
Now, we've seen a blaster shot hit snow before (ESB). The fact that it looks like only a "little" amount of the water is instantly vaporized (or, more likely the snow was just tossed up in the air from an explosive force), we can assume pretty conclusively that a blaster bolt carries less energy than a bowl of steaming hot lava.
2.) In all of the games we've seen, the only thing that seems anywhere near effective against Samus is physical attacks, particularly heavy concussions. At the beginning of Metroid Prime Samus gets thrown violently into a bulkhead, which damages some of her suit's components. At the ending of Metroid Fusion, Samus gets bludgeoned for about 1298 damage by the Omega Metroid.
A high power concussion really isn't something that Boba Fett is equipped to deal to Samus.
3.) On the Sarlacc note: Roll into the hole in Morph Ball mode, drop Power Bomb, Screw attack to safety. Fin.
[This message has been edited by Jon`C (edited April 12, 2004).]