Sometimes Marvel shows women in a sexist way. Other times they are shown in a very positive way. Think of Ms Marvel (pre dark reign) or Spider-girl. Now lets look at alot of the entertainment geared towards girls. Boys are either shown as idiots or as a sissy. Never as a fleshed out person with any kind of dimension. Girls get a much fairer shake in comics then boys get in most things geared towards women.
Comics and video games are the only medium boys have left.
The instances of women shown in a genuinely positive example in Marvel Comics should not be discounted, but they are not a microcosm of the genre's treatment of women.
And comics and video games are " the only medium boys have left "? Even putting aside the absurdity of the idea that a medium should belong to a single gender ( and your lack of use of the plural noun " mediums ", for that matter ), both mediums by and large have become more gender inclusive; games especially have seen a surge in product geared towards groups other than 18-34 year old males ( Nintendogs, the Sims, Harvest Moon, etc. ). And contrary to your opinion that entertainment geared towards girls by and large discriminates against boys, a lot of these games have plenty of male fans.
Change or die, it seems...