1. Be certain of what you aim to do.
=> You need the OS on SSD. But, you'd definitely install some programs besides the OS, except games. Problem is, you can wipe your laptop HDD (containing the OS along with those apps) and reinstalling windows to SSD, but then you'd loose all the apps you installed on laptop HDD. Say, MS Office, Adobe, etc.
2. Put your OS on HDD for now.
=> This may seem like a bad idea, but geofelt had a point in his post, laptop HDDs are usually 2.5" and really slow than conventional 3.5" desktop HDDs. Better put it on the HDD.
3. So what do you need to do then?
=> Situation: OS and games are on HDD. Solution: Make partitions! Put OS on one partition, when you get the SSD, erase that partition and clean install on SSD. Make sure the other partition(s) do not have any Windows dependent apps (programs) and only contain bulk files (docs, music, movies, games, etc). That way, you'll need to wipe a partition and clean install on SSD.