While I sympathize with this plight, having spent a couple of days struggling with a 20" iMac that refused to light up when booted into XP (eventual solution: remove half the RAM, reboot, reinstall RAM. Cutting head off of chicken and sprinkling holy water optional), I have to wonder if we're doing ourselves a service when we buy Macs with the express purpose of running Windows on them full-time.
I know of shops that are doing this -- I'm doing it at the day job -- but there is a fairly substantial degree of uncovered-behindness in the deployment of a beta solution with an OS unsupported on the hardware and no promise (until Leopard at least) of any help from the Motherfruit. In a sense, this is where someone running Linux on Dell gear is sitting -- fine as long as everything works, then out of luck when it doesn't.
Should Apple support XP, to the point of swapping hardware under warranty if it won't boot Windows but works fine in OS X? Let us know your thoughts.