HTPC and HD content - wired or wirelessly?

Hi. I'm a noob to this forum and HTPC, but I'm hoping to build an HTPC for my family in the near future, so I plan on reading as many beginner's guides as I can and gleaning as much information before purchasing anything.  Anyway, I have a question about HD content and the best medium for networking it through a home.  A few months ago I  spoke with a person at a website called Assassinhtpc.com and ask if steaming HD content wirelessly from an HTPC throughout a home was a reliable and stable method and his answer seem to indicate that it was not that stable of a medium at this time even though the HTPCs they build for customers have wireless capability. 

So, my question is, do you think that HD content is best served thru a wired network, i.e, Cat 5e, 6 or 6A or is it just as easy to stream wirelessly?  Just wanted to post this before I purchased any cable to see what the general consensus was.

Thanks for any input.