I cant help with the DS to Poser question but, as to whether or not you can install program files on a drive other than your main drive the answer is yes. Like you I have a small SSD main drive that I try to keep free of anything other than Windows and any system files. My secondary drive is a 750GB SSD/HDD hybrid which is where I install all my program files and then my runtimes are located on larger external drives. You just need to create a folder and name it Program Files on your secondary drive and be sure to nominate that as the install location when installing any software.