Ideas for pc upgrade

I have decided that I am going to be putting a little money (like $600)into my computer for upgrades to my system rather than spending that money on a ps4.

My hard drive is 100% full, my graphics card is out dated(9800gtx), and my processor has never been over clocked.

Any ideas on like a raid setup with HDD's, and a SSD, or a nice heat sink, or a cheap graphics card that I can run present and future games on, would be wonderful. I don't know anything anymore because of my absence and am really lost on the basics of computer needs now a days.

would I be able to buy a new hard drive or 2, and a raid controller, and still be able to use my existing hard drive?

See you in teamspeak

I have to talk to you about your system more, but I have many suggestions!

1. More Memory 8Gig.

2. Nvidia GTX 660 Ti or higher.

3. 2x SSD's 128gig or higher for Raid Boot and Gaming Volume, and another 1.5 or 2.0TB storage drive (cheap).

4. Let me help you set it up!