When you install windows on the SSD make sure the SSD is the only drive connected. Reconnect the HDD when you are done. You can move Data(doc, music, save games etc), and your steam apps folder since steam handles the install. But all programs, including office, must be reinstalled on the new windows. You will have to know your product key, or find it with a key reader.
So. Connect SSD only. Install/update windows. Connect HDD. Copy/back up any needed files/keys. Format HDD. Install programs under new OS and point the install location to either the SSD or HDD via custom/advanced install.
Edit: check for a firmware update for the SSD before doing anything. They ship with faulty ones sometimes. (looking at you OCZ)
But if you have game backup then no need to doing such thing. Just install steam on new SSD and restore backup apps. And always do steam apps backup for games in disc. Who knows, there could be a accident and need to install games again.
Install only os and most frequently used program like games on ssd. No need to fill up ssd with program like MS office.
You cant backup office. I asked you, if you have backup for office. So you can reinstall.
But you can backup steam apps from steam. To backup steam apps, Right-click the games from library and select backup file. If that grayed out, then click properties. Then select local file and then Backup. Now follow the instruction.