I'm sorta in same boat (have another post about XP 64b and gaming), and wondering is the "ability to utilize 4gb" over XP 32bs ~3gb really worth it.
I don't need anymore compat / driver issues...specially when you get into the "non mainstream" driver releases that are done / found in the general public...
My main question being will 4gb 64b be *Faster* (again, from a gaming standpoint) than ~3gb 32b. hopefully this answer will come out clearly somewhere.