I hear a LOT about Megadeth on forums I attend, and I've known about them for years now. My brother got me to listen to some of the albums, including Peace Sells, but Who's Buying?, Rust in Peace, and Countdown to Extinction. I haven't given any of them extra listens but I must say Megadeth is pretty good. Maybe Mustaine's voice is a little too rough and not melodic enough for me =/
Yes, I know about their coming album... it actually sounds promising. I heard "Kick the Chair" and it had some damn good riffing.