So far, conclusion is "this can't be done." The following method doesn't work because Windows 7 requires Legacy boot mode and Ubuntu requires UEFI. According to many, if you install Linux first, and then you try to install Windows as a dual boot option, Windows will rewrite your boot process and fuck it up so you can only boot into Windows. I think this happened to me once, too.
If you install Windows 7 first, you will have installed into Legacy and then I'm not sure what you would do for installing a second system using UEFI.
According to someone on a forum who was wondering the same thing, but it doesn't work (I don't think it worked for the person trying to do it either):
- Select UEFI mode, disable legacy mode, disable secure boot.
- Set SATA mode AHCI, disable RAID.
- (Reinstall Windows here if necessary.)
- Flash a USB install device
- Reboot, enter your system's one-time boot menu and select the install USB device from the UEFI devices list, not the legacy devices list.
- Install Linux.