How to add a new OS type in DS 7

Hi,

I'm currently trying to have a test on 64bit Windows 7 deployment.

When I configure the "Prepare for Image Capture task", "Windows 7 Professional Service Pack 1(x86)" is the only option showing in the OS type dropdown list as show in the attached picture.

I checked "All resources" in DS console, I can only find  "Windows 7 Professional Service Pack 1(x86)" in the "OS File Resource". Do I need to add a new OS resource as "Windows 7 Professional Service Pack 1(x64)" in order to select it in the OS type dropdown list? If so, how can I add OS resource in DS 7?

Look forward to your reply.