Hi, i work for a sequencing service called Functional Biosciences, Inc. We offer SNP resequencing, so I know how to do this if you're going to go with sequencing rather than probes etc.
Just do a PCR reaction, making sure to run negative controls alongside your DNA samples. Do an exo sap clean up of the pcr reaction. Sequence from both directions using ABI big dye v 3.1, just use the pcr primers if the band on the gel looks clean. Theres a program called Mutation Surveyor that will analyze the traces at the polymorphic site. It can objectively designate each sample as a heterozygote or either type of homozygote. We have this software at our lab, its decent. Otherwise i think theres some free snp software here, [
snp.wustl.edu]
but i havent used any of it.