Could Pregnancy Occur?

I've been getting all different dates online for ovulation. The first day of my last period was 8/22/08. We had unprotected sex all weekend, last time being this morning. Is there a possibility of the sperm being able to live long enough to fertilize the egg? I just checked on an ovulation calendar and it said my most fertile day would be 9/4 but I've also gotten dates like 9/8 last week.