Well the SSD sounds like a big plus, the PSU may be a keeper, you will need a new MB,CPU,and RAM if playing games a new GPU. I would also be looking at a new case.
Why would you say new case, airflow i am assuming? The case currently has 3 fans in it...can i swiss cheese this thing?
Ram is covered, currently have 8gb of ddr3 salavaged from a another pc that was being tossed out at work, win