When/if I install snow leopard, will I need to repartition my hard drive to run Windows? I know it sucks, but one application I use for work doesn't work on Mac. It was a cost-saving thing.
If you already have a Windows partition you will not need to reinstall Windows via Bootcamp after upgrading to Snow Leopard.
Your drive will not be changed in any way except that Snow Leopard will be installed on it. If you are using VMWare Fusion or Parallels 4 (I hear that Parallels 3 or lower does not work with Snow Leopard) with a virtual Windows PC Hard Drive file, you will not have to partition your drive to run Windows.
If you prefer to boot into Windows, then, yes, you should repartition the HD but that can be done after installing Snow Leopard.