The spread of good mutations in sexually reproducing organizms

In sexually reproducing organisms how do good mutations overcome both genetic drift and genetic burden?Genetic drift maintains the status quo quite well, but if you minimize genetic drift by having an inbred population harmful mutations will quickly build up and weaken the entire population since the majority of mutations will always decrease rather than increase general health.How do both genetic drift and genetic burden get overcome so that a good mutation can both spread through the population and not be coupled with many bad mutations?

lol, holy cow was my understanding off! I'm not even sure I have a question to post anymore.well, I have to go to work, I'll look at this again later....This message has been edited by mrjeremy, 12-22-2005 09:50 AM