I think they convert for a few reasons such as:
they fall in love with muslims guys, as there are many here in britain and everywhere now. Check this in youtube
http://www.youtube.com/watch?v=PN62a683ibw (why the muslim population is growing bigger and they are neally reaching the amount of all of other clasification of european...)
,the muslims population is growing not due to converts but because (original muslim inmigrants makes lots of babies, more than european families)....and so there are many muslims guys, they fall in love with them and women are more crazy than men when they fall in love, they give everything...they are more passionate....well that is one thing, and also due to the Islamic new tv and radio programmes, all the propaganda out there, makes curious people wanna know.....and then women are much easier to harrass, than a male, male muslims feel less intimidated when triying to convince a woman that a man, and bit by bit, by brainwashing and spitting out to these pour women the threats of hell, it creates a psychological effect on them, a fear that doesn't leave for any rationality that causes them to submitt without questioning....and the end!