222Rem -- First of all welcome to the world of dSLR, you won't be disappointed with the quality of digital files today. Outstanding results can be had, with very modest gear in most cases.
It seems like you're leaning towards Canon at the moment, and that's definitely the correct choice in your situation, starting from the ground up.
The 5D is a great camera, and it would be a very long time before you felt it was dated. Sure new bodies will come out, but unless you're the type of fellow that must be on the very cutting edge of technology, your 5D will not NEED to be replaced with a newer version for many years. Canon customer service is second to none, which is important in your situation since over the course of MANY years with a dSLR, a small repair may be needed here and there. You'll be out of commission for a very short period of time, as Canon's turnaround time is very fast in this regard.
What are some of the type of images you're looking to achieve?, and we'll can help direct you toward some lenses. You'll be much happier with Canon glass, as this is the reason most people go with Canon to start with. No doubt Sigma and others make some very good lenses, and you may want to look at a couple, but in general Canon glass is the best there is and the 5D really deserves it and can make it shine.
