Are you doing an official upgrade, or a clean install?
If I were doing a clean install, I would disconnect the old HD, connect the new SSD. Proceed to install a clean copy of Windows 8. Then once everything is set up, add the second hard drive - make sure in your BIOS that you have the SSD boot priority set FIRST so it boots to the SSD, not the old HD. Then, copy over any old files from your old HD that you still want and then format that sucker. You can use it as a storage drive or whatever.
If you're doing an upgrade, I would install the SSD and then format it in Windows 7. Use a utility to image your current drive over to the SSD. There are tons of utilities, I've used EaseUS and it's pretty easy and straightforward. Then remove the old HD, and boot to the new SSD. Proceed to upgrade to Windows 8. Then re-add the old HD again making sure BIOS is set up to boot to the SSD first. Make sure you have all files needed and format it. This will only work if the size of the data you are trying to image to the SSD is SMALLER in size than the maximum capacity of the SSD. If not, you'll need to find a place to store stuff before you can do the image.