yeah, it's hereditary. look at your grandfather on your mother's side AND your dad. it's not one or the other but both. so if both have their hair, then you should be in the clear. if one of them is bald, then your chances aren't so great. if both are bald, grab the mach3.
prescriptions for hair are: rogaine, propecia, and dutasteride (that i know of). unfortunately, if the hair follicles have died then none of these prescriptions will help. lot's of people take a rogaine/propecia combo to regrow hair and dutasteride is the new kid on the block. it seems like a stronger form of propecia. saw palmetto is a natural variant that has the same effects as propecia and dutasteride (but weaker and also much milder side effects), so if you're afraid of losing your hair then maybe taking saw palmetto will slow/stop/ or regrow (not too sure on the regrow part) your hair until you decide that maybe a prescription might be more beneficial.
and if you're hanging on a few strands, please... please just cut it off or trim the rest of your hair short. it's not fooling anyone and just accentuates the balding.
edit: oh yeah, finasteride (propecia/proscar) and dutasteride's side effects are decreased sex drive, decreased ejaculation fluid, possibility of not being able to maintain an erection, and gyno. some people exhibit none, some people all (i haven't read about any gyno cases yet though).