XBox didn't have better spec, I'm sure my PC was faster at the time. Let me think...
Yeah, I had a Pentium 3 667 overclocked to 750. I had 128MB of RAM. The weak link was a Geforce 2 MX card, but that was only because I couldn't afford the Geforce 4s which were out then.
And considering I was behind the curve at the time, I think it's fair to say that PCs were better than the XBox even back then.
As for brand buying... Why not? Sony make damn good audio goods, so if I were to buy a personal stereo I'd make it a Walkman. Creative make very good PC audio stuff, so the jukebox I got is made by them (excusing all the proprietary filesystem crap, it is the nicest of the lot), and Canon make some of the best imaging products in the world, and I'd love to own a scanner, high end printer, and digital camera all made by them.
So sometimes brand loyalty is a good thing.