Most conventional loans will require a minimum credit score in the 620 - 640 range, though the preferred target is 680 and above. (Reference: http://www.rurdev.usda.gov/SupportDocuments/CA-SFH-GRHUnderwritingGuide.pdf). FHA loans, on the other hand, do accept a lower score but be prepared for higher fees and interest rates. FHA's website states: "Minimum credit score requirements for FHA home loans depend on which FHA loan product the applicant needs. Generally speaking, to get maximum financing on typical new home purchases, applicants should have a credit score of 580 or better. Those with credit scores between 500 and 579 are, according the the FHA guidelines, 'limited to 90 percent LTV'." (Reference: http://www.fha.com/fha_article.cfm?id=200.)
The best way to find out if you can qualify for a mortgage is to go on down to a lender and get pre-approved.