RDRAM is great, but it will soon be outclassed by DDR2 . . . can't improve on something that won't be bought.
Intel generally has better manufacturing capabilities, lower heat and increased reliability are the outcome. Sadly, Intel gives less than half a crap of what they make. They rarely answer any technical challenge without resorting to deeper pipes and thus higher clocks. This ended in them resorting to ripping of AMD processors to get any performance gains. HT is great, but ever wonder why they haven't been able to ramp up speeds like they did through the PIII to P4's?
AMD on the otherhand, has taken a brilliant approach to die design, and I find their chips to be much better engineered. The fact that a much slower AMD can beat on a much faster P4 or celeron is proof enough. At equal clocks, the AMD will always be faster. Sadly, AMD has problems manufacturing their great designs, and constantly depend on other manufacturers (Motorola and IBM) to make their chips and implement new processes.
Then it comes down to cost . . . If AMD is almost as good as any given pentium in most things, and much better in branch prediction, pipe usage, floating point math (it takes 4 on die math processors in the P4 to come second place to AMD's lone on die math processor) and memory management, why am I going to pay 60% more for an Intel based system?
If you factor in the awesome power of Nvidia's Nforce AMD chipset, then you can't deny that it's difficult to beat AMD in any sensible contest.
Some people see Intel's prices tag and think premium, I see it and think bloat.