Had you correctly unplugged the other HD's during Windows 7 install you would have been given the C letter on the SSD and could boot it independently via BIOS which is the best way with separate HD's. You can either reinstall to realigned SSD, or unplug all other drives now, mark Windows 7 partition active, then run Startup Repair to write the System MBR to Windows 7 partition. Partition - Mark as Active Startup Repair - Run 3 Separate Times
Since you didn't tell us what is on the other partitions, we have to guess that your old Windows 7 is on C. If you want to get rid of it then you can simply delete it in Disk Management since D (Vista?) holds the System MBR for DISK0 Then if you want to continue using the Windows-managed Dual Boot to choose between Vistas, simply boot DISK0 using the one-time BIOS Boot menu key given on first boot screen. Delete the Windows 7 listings using EasyBCD to Edit OS.
However if you want to configure your three separate HD's with OS's to boot via the BIOS, remove all listings on the EasyBCD Edit OS tab. Now boot DISK0 when needed by tapping the one-time BIOS Boot Menu key given on first boot screen.
To boot DISK2 (if that's where your other Vista resides), you'll need to recover the System MBR into it the same way as you did DISK1, by unplugging all other HD's, marking it Active and running Startup Repair from the Vista DVD.