CPU Upgrade

Every time you get a new motherboard, or switch chipsets, you will have to reinstall windows.

A good choice would an i3-2100 and an ASRock Z77 Extreme 4 and 8GB of DDR3 memory.

Prefer AMD? Why? For the price?
They're cheaper for a reason. They're not as good as Intel processors.
Exactly which processor do you have? It's unlikely that you'll be able to upgrade just your processor, because you motherboard probably won't support the latest CPUs.
If you're willing to push your budget a little bit, Micro Center will bundle a Z77 motherboard and LGA 1155 CPU for $50 less. And CPUs cost less at Micro Center anyway.

i did some research and found this and my mob supports this http://www.cpu-upgrade.com/mb-Intel_(chipsets)/H61_Express.html

Are you sure? Because if your MoBo supports LGA 1155, well you can leap for joy.  
Head over to Micro Center (if you live near one) and pick up an i5-3570K.
I just got one myself. It runs at 3.4 Ghz stock. Overclocked it to 4.3 GHz and it's as cool as a panda.
My graphics cards come in later today so I'll let you know how it games.

What's your current graphics setup? That's more important for gaming.

And yes, I know the i5-3570K is not on the list in the link, but if your MoBo can take the i7-3770, which has a 22 nm architecture, I don't see why it will not take the i5-3570K.

I run a Radeon hd 6670 2gb ddr3 also with 8gb ram and can run most games max but on games like gb3 and arma 2 my cpu ist powerful enough to run so....I play mw2 mw3 waw etc so i will see or ill buy one off amazon dont live by a micro center but i will look around

also i read that you do not have to reinstall windows unless you upgrade motherboard

I can't speak from experience about reinstalling Windows after upgrading components, but if you upgrade your CPU, I really don't think you'll have to reinstall Windows.
It's always good to have a backup, though.

It'll stretch your budget a little bit, but if you really want to have some gaming fun, pick this up: http://www.tigerdirect.com/applications/SearchTools/ite...

It's totally not necessary, if you're happy with your gaming performance.