Originally Posted by Finks
I don't know why HTC decided to put in a smaller processor, it would have been a no-brainer "perfect phone" for me!!
By "smaller" I assume you mean "less MHz"? If so then mere numbers are misleading.... the CPU in the Z is a generation (at least) ahead of that in the Desire so it's more efficient and the Adreno 205 GPU gives greatly improved graphics performance.
Btw, the 800MHz is an underclock; the MSM7230's native clock is 1GHz.