Where are you going to put the SSD? Laptop or desktop? If laptop, chances are you have one drive bay and will need a bigger drive. 120gb is kinda small. If desktop, use the ssd as your boot drive and have your data on the traditional hdd.

I personally use a crucial M500 480gb ssd. The reason I chose crucial was cost and I only use one laptop. No desktop. So had to get the biggest ssd i can afford. Got it on sale during boxing week. Its fast. Very noticeable on boot up, shut down and opening programs. I just cloned my old hdd. Did not do a clean install bec I dont have an optical drive. Had I done a clean install, chances are it will perform better and faster.

An option is to get a Seagate hybrid drive. Its a traditional hdd with a small ssd that makes it perform faster than a normal hdd but less performance than ssd.