Make no mistake I miss playing the board game, there's no replacement for that. But with megamek at least you don't have to go out and buy all the stuff until you know you have people to play with.
Also just to relate a story, a few months ago my family had to take a day and a half road trip, so my little brother and I loaded it up on two netbooks and played a network game right there in the car. It was quite a bit of fun since there was certainly no room for the full board game there in the back seat.