ronintexas :
Your hard drive should still work with the new SSD. Just install the OS on the drive with the hard drive unplugged, then add it in.
Exactly.
While it's not necessary to unplug the HDD it's a very good idea to prevent accidentally wiping any data.
Other:
1) When you attach the HDD again (after Windows is installed) when you reboot there's a chance it will try to boot from the hard drive instead of the SSD.
If so, just boot into the BIOS and change the default Boot Order so the SSD is listed first.
2) In the FUTURE, I recommend using a program like Acronis True Image to make periodic backup Images. The FREE (manual only) version from Seagate is called "DiscWizard".
So after you have everything running again, download and install DiscWizard then make a backup of your SSD to the HDD (full compression). Decide later if you want to buy the full version and automate it to a weekly backup (Main + incremental).