When you installed to the HDD the Ubuntu bootloader was also most likely installed to that same drive. Since your BIOS 'boot order' probably lists the SSD above the HDD, your bootloader (GRUB) isn't part of the boot process. It's there and set correctly, but it's just being skipped when your system checks the Windows drive and finds a boot partition there.
You can either try booting from a live CD/USB and 'repair GRUB' by installing it to the SSD, or change the boot order of the drives in the BIOS.
I would try changing the BIOS setting first, that's the easiest.
EDIT Sorry I just realized I read the question wrong. You can probably still fix things by following the 'repair GRUB' link though. Once you get the Windows entry in GRUB, here is a post explaining how to make it default.