howdy Jimb086 (love the avatar)

if you want to have more then 4G of system memory available, you must have a 64 bit OS (i'm not going to address the tweaks they made to 32bit stuff to make it work above 4G). the main reason is that 32 bits == 2 ^ 32 == ~4G addressable memory. to address more, you need more bits... so, 64 bit (loads and loads of addressable memory)

at this point, all indications are that windows7 performs much better then vista. (my guess would be that it's a result of removing the winsxs subsystem)

hope that helps,

Rob