the processor doesn't affect your ability to format, unles it doesn't work of course....
I would recommend NTFS unless you're running an OS that doesn't support it.
formatting means you lose everything on the hard drive, so be sure to back your stuff up first, onto portable media like CD's.
you can use your OS CD to format. just go through the install process. before it actually starts to install, it will ask you if you want to format using NTFS, FAT (quick or not) or to leave the drive intact. choose format to NTFS.