alan, seems correct, except that you forgot to mention Celeron, which is about 50% of Intel unit sales or so (I don't know exactly).
For AMD, it boils down to brand recognition now. The problem is, if you look back into all the 2003, Athlon XP was offering at least twice better price/performance comparing to Celeron. It means AMD brand was twice worse than Intel, that they need to undercut Intel prices by 50% to sell.
This is not happening even in auto industry. It's hard to find two mainstream car brands with 2x difference in price.
Even today, with Athlon 64, AMD is not that much better. Compare equivalent processors A64 3000 $213 and P4 3.2 $369. AMD has to undercut Intel by 40% to sell.
If magic happens and AMD will have to undercut Intel only by 30% in price, that will increase AMD sales by 20% without units sales increase.
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