Having more than 4GB of RAM can, even with a 32 bit operating system such as XP, be allocated to become a RAM drive. Using that for video rendering really brings thing to life, especially if you only have a single physical hard drive in your machine.
The other benefit to this is running virtual machines. The extra RAM certainly make things step up in pace.
Maybe I am a RAM addict but at the prices available, it is an affordable addiction.