Downgrading my laptop OS to XP from Vista has been quite frustrating. Initial streamlining of XP cd with SATA drivers (using nlite) and scrambling with BIOS settings aside, the most irritating aspect of running XP on this laptop has been incompatible/buggy drivers.
The Realtek soundcard and modem share the same bus, causing some conflicts. Initially device manager reports Modem for improperly installation, after a lot of trials when it does recognize the modem properly, a "Conexant API system" shows up as Corrupted. I believe this was the primary cause for the innumerable and persistent crashes in Fallout 3 on my system.
The videocard drivers as usual cannot be installed directly from nvidia's website and have to be encased in a "Dell wrapper". The worst part however is with a bug in the wireless driver. For Intel 3945abg card, the driver versions 22.214.171.124 and above start freezing the network connection- especially when I try to connect to gmail with chat enabled and so on. Two ways to get around this are to downgrade to 126.96.36.199 and/or set the power management in configuration of wireless adapter to "highest power" setting.