Did some more poking around. The EFI utility simply allows me to browse files on the drives. Doesn't let me set EFI boot order, but there is an EFI boot order. It's just that hard drives aren't included there individually. Windows Boot Loader is first, followed by the various removable media.
I tried disabling SATA1 in the legacy boot order, but with SATA1 disabled, when I launch the Windows Boot Loader and select Windows 7, it says there's no OS. In other words, it's trying to boot from SATA1, which is disabled. Also, when I try to 'legacy boot' off of either SATA0 or SATA1, I get the PCLOS grub loader from SATA1. I'm beginning to think that there's something in hardware making the system think SATA1 is[/] SATA0 (at boot time, at least). How else to explain 'legacy boot' loading from SATA1 when I ask it to load from SATA0? Unless the BIOS says 'there's no MBR on SATA0, so I guess he meant SATA1 - even though he said SATA0'. Either way, the gparted rescue disk (and the EFI utility - for that matter) can both see both drives, so they are both individually addressable.
None of this addresses why the Windows Boot Loader in EFI mode insists on trying to boot the MBR from SATA1 instead of booting Windows 7. Except that the Windows Boot Loader is some kind of mini-OS, and it must be labEling SATA1 as the C: drive when it's present and then following its instructions to boot from C:. Again, when SATA1 is not present, Windows 7 boots normally - and labels the same drive in SATA3 as the F: drive. Sheesh!!!