AC Polarity

I'm in a house that is about 75 years old and have a pretty nice system (Muse, NAD, Martin-Logan, etc.) along with my TV, VCR's, etc. and am going to replace the prewar electrical outlets in my living room. What I'd like to know is which side of an outlet is the 'hot' side. I am wondering if electricians wire all outlets the same way, say, putting the 'hot' on the side that has the slot for the wide blade on a modern 3 wire outlet. Any info welcome.