(New Build) Fx 8320 or i5 3570 for my PSU?

Hello guys,

I am upgrading my system which is a 2006 build.

Present specs:

Core 2 Duo @2.2ghz
Ram 2gb DDR2 @667mhz

Mobo: Gigabyte GA775 945GM S2
PSU: Generic 300 Watts
No Gpu using integrated one.

What i plan:

I already have got a Corsair CX430V2UK psu + Xfx 6750 graphics card and 1tb WD Green HDD + 160gb WD HDD + Corsair Vengenace 4gb @1600mhz

Now i am confused between what processor i should go for and if my psu can handle it.

Requirements:

Watching Movies
Gaming (i want to play latest games at respectable fps around 40)
Video Encoding (amateur)
No SLI or Crossfire
No overclocking

I have a monitor with native res 1400x900 which i wont upgrade for 2 years or more.

So..

Which processor should i go for?

AMD one is cheaper by 50bucks then i5.. and got more punch but idk if my psu can handle it.

But the mobo choice for i5 is good and i found this Link: http://www.flipkart.com/gigabyte-ga-b75m-d3h-motherboar...
for under 100$ with USb 3.0 Sata 3 and 32gb ram support.

I need advice on a good mobo for AMD (if suggested) under 100$.

So what you guys think?  

PS: I can disable some cores on AMD to save power (if possible) until i can get a better gpu cuz cor me its a bigger upgrade from core 2 duo even after all pruning.