yes, it's true that the speed is limited. worse, after the installation there is no guarentee that you can change the setting back since that'd be a major hardware change and windows would either refuse to boot or at best require re-activation.
If I recall correctly the way to get around this issue is to slip stream SATA drivers into the windows XP install image then burn a new disc.
if you google slipstream XP you should find a guide on the microsoft website telling you how to do this,