There's no need to pirate; you can download the ISOs for Windows 7 installation media directly from Microsoft (well, okay, Digital River's hosting the download but whatever), free of charge.
32-bit Windows 7 Home Premium
64-bit Windows 7 Home Premium
32-bit Windows 7 Professional
64-bit Windows 7 Professional
Links taken from here. I can't personally confirm they're live, but I've done this in the past and they look the same as I remember.
EDIT: Removed Ultimate links since they appear to be dead, but they're out there. Somebody feel free to comment and/or edit these in.