The Windows 7 Upgrades (and Retail packages when they are released) will have both 32-bit and 64-bit disks, with the choice of which to use left up to you. I would suggest, especially having more than 4 GB of RAM, to definitely install the 64-bit version. I'm assuming because you have 5 GB of RAM you also have a processor from the last couple years so 32-bit vs 64-bit shouldn't be an issue.
So, to sum up, yes, it will contain a 64-bit install disk.
okay.. i have xp installed. 32bit.. so im not getting all my RAM as we all know.. i have heard u cant do an upgrade from 32bit to 64bit.. but last time i used an upgrade install disk i didn't have a windows install on my computer.. the installer asked me to insert a windows cd to verify i own one.. i did. and it proceed with a clean install.. so can i do the same.. or do i have to have a actual install on the drive to use the windows 7 upgrade?