The link to the drivers page for Vista 32 bit is here:
http://h10025.www1.hp.com/ewfrf/wc/softwareList?os=2093&lc=en&dlc=&cc=us&product=3747345&lang=Get the Summer 2008 SATA controller driver. Drop it on a memory pen or disk or something that Vista PE can read and point setup that way when it gets to the option.