You can add a SSD for the OS drive and that would make the overall perfomance of the Pc a little snappier and programs would open faster and web pages too.
What specificaly do you want to speed up , productivity or gaming? What OS do you have?
This is a chart of all the video cards and where they fall in order from top to bottom and which cards from each comany compares to the other. It looks like a 6870 or a 560Ti would be an upgrade for the video card. How much are you looking to spend on this upgrade.
I still use XP pro, and I am trying enhance the overall perfomance. I want to see what I can get out of this system, to avoid the expense of an
entire system make over. By the way, I am using an SSD for my OSdrive.