Simple n easiest to do if you are afraid of invalidateing your Warranty....
Buy another 2.5" HDD, FORMAT it---take the one out that has Vista on it, install New un n install XP on it..
BUT! Make sure you got ALL drivers first and with the FireWire n Sound drivers there is a util, (utilities driver) install that first or ya sound might not work..
To run in compatibilty mode...
Right click on the program icon.
Choose properties --> then Compatibilty
Tick the box 'Run in compatibilty mode for' and choose xp from drop down menu.
You can also tick run as adminstrator.
I have more people happy with Vista now. It's not crap but just a learning process ..