As they title says.

My current setup is as follows.
CPU:     Pentium Dual-Core CPU E5200 @ 2.50GHz
RAM:     4x 1GB Corsair XMS2 PC2-6400
MOBO:  ASUS P5Q-PRO P45
GPU:     512Mb GeForce 9800 GTX/9800 GTX+
HD:       2 x 500Gb WD Caviar Black in RAID 0
            1 x 1Tb WD Caviar Blue
OS:       Windows 7 Pro 64bit

I game and this was fine for the last 2 years and it still does the job and a good one at that.
I can overclock this setup no worries to 333Mhz with a x10 multiplier with a average Vcore
and no temperature difference but it's had a rough history with me trying to get the highest
stale OC possible and doesn't like being clocked for long periods as its not stable anymore.
SOoooOOoooOOOOo i'm keen to upgrade or do a new build.

So here are my questions,
1) Any good programs to see exactly what the bottle neck is?
2) Your guess at the bottle neck??
3) Would you upgrade or do a new build? If so what would you do?

With new technology coming up and us being at a current stand still before the next big move
I believe now is a good time to do this as I don't like spending heaps!

My current thoughts are:
CPU:     Intel core i3 530 (clocked past the 540)
RAM:     2x 2Gb OCZ Gold DDR3
MOBO:  Gigabyte GA-H55M-USB3
GPU:     1Gb Sapphire Radeon HD5850
HD:       ?????

OS:       Windows 7 Pro 64bit