If you know R and how to use it, is better for you that take a look at Bioconductor and see the packages to deal with this kind of data. There are several
I think you may be more specific by stating what type of studies you are doing ! That is because family based studies are different from population based ones. If you are studying a Mendelian trait and planning to do linkage analysis then I recommend using Merlin as it is very powerful in handling such huge data. However If you are studying a complex phenotype I think PLINK is very useful in this case.