Since this looks like more to generic question, I will provide some answer

SSD provide speeds, but price per GB is still too expensive. You got more speed but with less space.
Regular spinning HDDs can provide more space but can't provide great speed. Imagine 500~MB/s SSD vs 70~120MB/s HDD.
mSATA is a SATA port, as micro USB to USB. Its basically the same but smaller in size and of course, smaller SSD. Since its smaller, some SSD products might be slower compared to its regular 2.5" version.
If you need both speed and size, I recommend go with SSD (around 64-240GB) + HDD, install OS and primary apps in SSD and the rest, data, games inside regular HDD.
If you want a game to load faster, then choosing SSD with big space is wise for you. If your games and apps doesn't takes as many space, using 64GB-120GB single SSD might be enough.
If you are tight in budget, you can add SSD later.
Here a basic calculator:
Windows is usually around 16GB
Essential apps (Office, Multimedia, Photo editing) is around 10-20GB
Games from big company usually take at least 4GB per game. Nowadays it usually takes at least 12-20GB per game.
Indie and small games usually takes only few MBs to around 4GB per game.
For me, I like my windows and applications to start and loading fast, but I don't care much about the game loading time. Still I have a lot of data to store. So I will choose SSD for windows and apps and a big HDD to store data and games.
Choose wisely
This post has been edited by syahmixp: Jul 23 2014, 02:53 PM