BigMexicant, sperm can live up to that long in the female reproductive tract, but they usually don't. That's just the outside limit. The pH (acid balance) in the vagina is actually very hostile to sperm, and so the ones that live longest are the ones that move on up into the uterus and fallopian tubes, where they're away from the more acidic environment. As far as how long sperm lives after ejaculation, I think that just depends. (Read the link below for some interesting facts.) I know it can live long enough to be examined in a lab in a test tube or under a microscope because fertility doctors do that all the time, but it doesn't sound like it stays viable for very long.
http://babymed.com/faq/content.aspx?448