no, it wont be that easy to install XP, the file system in Vista and XP differs. you need to wipe clean the H/D to get XP on.
Darik's Boot and Nuke (Hard Drive Disk Wipe)
download this free utility to clean the hard drive (fairly easy process), then you will be able to install XP, else keep trying, it wont install XP.
and laptop fan turning ON few minutes is OK, as your laptop came with onboard graphics, and vista being pretty heavy on graphics, so your CPU has to do 50% of the GPU's work. and moving around XP means, graphics power needed. which puts loads on your CPU, ultimately turning on the FAN.