Male Baldness Info

I’m 24 with some thinning hair around the front of my head, I don’t have a bald or thinning spot on the crown/top part of my head, that area is thick and alright, no problem, so i dont think its “male pattern baldness” as I only have the thinning in front. I always had very thick hair growing up, my dad is 64 with thick hair, his dad died at 84 with thick hair. My mom, before she died, always said good things about my hair and that her relatives had good hair as well, so i dont know whats going on here.
I’m gonna book an appointment with a dermatologist, but I was wondering can I use rogaine or prophecia (sp?)? Cuz I heard rogaine only works if you have thinning/balding on the “top” of your head, where as I only have it on the front, is that true?
Here’s a couple of pics of what I have:http://img403.imageshack.us/img403/3721/…http://img14.imageshack.us/img14/9185/ph…

im a 20 year old healthy male and i have male pattern baldness and my hairline is already thinning, not bad but getting more and more noticeable. ive been prescribed propecia. has anyone whos takin this or similar pills have results? if so please describe ( hair regrowth, less hair loss, etc ) any side effects?