Only 128 megs... you should be able to install DOS on that (y)
Assuming you meant 128GB, you can pretty much install all your programs on there. Move your documents, pictures, music etc. to the HDD as they don't get any benefit from being on an SSD, but programs and applications definitely will. You can also install some games on the SSD for improved load time, but games nowadays take up huge amounts of space so just install the ones you play the most.