Agree with Ken: You probably want 32 bit unless you plan to double RAM, and cannot run a 64 bit installer from a 32 bit OS, even mounting the image.
Burn the RTM to DVD using ImgBurn at 4x speed with Verify.
Then boot from the DVD, keep ethernet plugged and "connect to the internet during install" to get latest
drivers/updates into installer, select Custom install, use Drive tools there to delete all partitions, create New partition(s) as you wish, then format before installing Windows 7 to first partition.
You should attempt to make Recovery disks first from the Recov partition, but it will become disabled during install so can be deleted after disks are made.