I'd also like to hear an answer to this. I'm confused about what a good customization is in regards to SSD/HDD, price & performance-wise.
I'm also considering the NP9170. Even wondering if I should go all SSD no HDD.
If your computing needs are satisfied by a 128gb SSd then you can however some factors to keep in mind:
1) You cannot do not & should not defragment or format an SSD
2) Repeated flashing like downloading movies and stuff and then erasing them, if you are into this you would need a seperate SATA disk for it as repeated flashing of SSD when it is the boot drive makes it unstable and decreses the life of the SSD
Hybrid drives like the Seagate mommentus 750 Gb has only enough storage for your OS so if you want o put games so that they dont crash and load faster then you would have to go for two seperate harddisks SATA & SSD.Otherwise if boot time is the priority then you can go for a Hybrid drive with just the OS in it