Since Dell and Microsoft don't make it friendly to allow you to install your legit copy of Windows XP on an Inspiron 531 I have found the main drivers to help things along.
NOTE: even though Dell does not officially provide Windows XP drivers for the Inspiron 531 it is NOT illegal to do this if the drivers can be had. This is per Dell support.
Good Luck and I hope this helps.
Drivers include:
1. 19-1 Bluetooth Module
2. RealTek HD Audio drivers
3. Nvidia Video and Network drivers
4. AMD processor driver (i must confess i am not sure what this one is for)
NOTE2: don't forget to run windows update since you do have a legit copy of Windows XP. At least I do....