Is my GT 430 bottleneck my perfomance? or is there any other factor?

Question

I have a performance issue lately with my computer and here is my computer spec,

Intel i5-2500k
Nvidia GT 430
8GB of RAM (DDR3)
With motherboard, ASUS P8H61-M LE
OS : Windows 7 64 bit

What i want is an upgrade for my graphics cards
Will i see a huge performance boost?

And if i must change the graphics cards do i need to upgrade the motherboard as well?
for PCI-E compatibility.

I use my computer for many things...

Thanks for the help!
And sorry for my noobness and english...

Edited : to make the post shorter

Answer 1

That graphics card was already low end when it came out. Just buy a new one. You can go high-end without problems, your CPU is plenty fast.

The brands are NVIDIA and AMD (formerly ATI) by the way.