Depends on your current cash situation...if you have the money to throw down on a major new build do it otherwise just upgrade...I built a rig very similar for a buddy with that exact board and cpu....I threw a CM Hyper 212+ cooler on the cpu and oc'ed it to 4.2ghz easy with more room to push higher (cooler is sick load temps at that speed are like 51c)......if I were you I would OC your cpu and get another 4gbs or RAM and then get a new video card and call it a day.......how much money you looking to spend? We can use that to determine what gpu you could get.
Gaming is usually much more dependent on the graphics card than the cpu.
I think I would do the upgrade in two steps.
1) Upgrade to the strongest graphics card you feel comfortable paying for.
Make it a significant jump, or you may be disappointed. Something like a GTX570/GTX670, or 7850/7970.
In a week or two, we should see the GTX660 launch which may well be an great competitor int the $300 price range.
Yes, you will get higher fps with a very strong card, but you will also enable more eye candy and a better minimum fps.
Also, ram is cheap. Upgrade to 8gb, assuming you have a 64 bit os. A demand page fault acts like a momentary stoppage of your cpu.
2) On the cpu side, you may be better than you think. Few games use more than 2 or 3 cores.
I think I would defer the cpu upgrade until you know how many cores you really need. Later this year, the ivy bridge duo's will arrive at a lower price point than today's gaming kings the 3570K or 2500K
Then I think I will upgrade to a GTX 570. And up my RAM also. Any suggestions on what hardware to get for RAM upgrade?
Good question on the ram.
In theory, you want to replace your 4gb with a supported 8gb kit.
Speed does not matter.
Ram is sold in kits for a reason.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards can be very sensitive to this.
That is why ram vendors will not support ram that is not bought in one kit.
Although, I think the problem has lessened with the newer Intel chipsets. Still,
it is safer to get what you need in one kit.
You want documented ram compatibility. If you should ever have a problem, you want supported ram.
Otherwise, you risk a finger pointing battle between the ram and motherboard support sites, claiming "not my problem".
One place to check is your motherboards web site.
Look for the ram QVL list. It lists all of the ram kits that have been tested with that particular motherboard.
Sometimes the QVL list is not updated after the motherboard is released.
For more current info, go to a ram vendor's web site and access their ram selection configurator.
Enter your motherboard, and you will get a list of compatible ram kits.
While today's motherboards are more tolerant of different ram, it makes sense to buy ram that is known to work and is supported.
Now all that said, your chances of a good upgrade is high if you just add an identical 4gb kit to what you have.
Or, tp be perfectly safe, just get a compatible 8gb kit; ram is relatively cheap.