Backup & Restore Individual files?

Hello,

After doing the initial Backup, as files change on my Computer (Updates, more new files, edit old files), how do I save - backup so the old original Backup is changed accordingly without my having to do a complete Backup every time?

In other words does Backup identify new files and just copy them instead of a complete repeat of a total new Backup?

&

I have two Windows 7 machines, 1. 32 bit windows Home edition & 2. Windows 64 bit Ultimate. Is it the same method for both?

Thanks

What app do you use?