You can try WINE or crossover for games as
amdfangirl suggested or Transgaming's Cedega ( both are based on WINE ).
WINE is free and open source ( $0 ).
crossover for games and Cedega are commercial.
Some linkage to get you going
http://winehq.org/
http://www.codeweavers.com/products/
http://www.transgaming.com/
Good luck