I am going to purchase a XPS 700 system in the near future I do a lot of video and photo work, I want at least 2GB of ram and was thinking of getting 4GB, I noticed that Dell says that a system configured with 4GB of memory will have a total available memory of less than 4GB because to fully utilize 4GB you need a 64 bit enabled processor and 64 bit OS.

Dose anyone know how much less that 4GB the system would have? Would I be better of getting 2GB and putting the 300.00 saved toward the next fastest processor ?