Here's a nice FYI site:
Fixing moldy basements - vapor barriers can be a bad idea
"Seal the concrete with a silicate based sealer, such as the products from
endur-o-seal. These are sprayed on to the cement with a garden sprayer, soak into the cement and fill the pores with a solution that gels and then hardens over a period of several days."
For products mentioned above:
Endur-O-Seal USA, Inc. - Manufacturer of Concrete Sealers, Stains, Coatings and Repair Epoxies