K.,
Welcome to homeschooling! I just started homeschooling my children and I love it.
There are numerous options as far as curriculum - in fact sometimes it gets a little overwhelming. It is all going to depend on what you want (Christian centered or not) and the method you want to use (workbooks,etc.). Mardel's has a limited amount of homeschool material. There is a store in downtown Lewisville that carries much more (sorry, I can't remember their name).
I strongly encourage you to join some kind of a support group. I am a member of Frisco HIS. This group is a Christian based support system that offers information and advice on everything. Their web address is www.friscohis.org. There is also a "subgroup" called Great Starts for people just like you. There are also groups in Plano.
Good luck! If you have any additional questions, please feel free to contact me.
D.