Help with Overclocking and buying A GPU w/o Bottle-necking

OK so heres my rig right now

WNDWS 7 (64 bit)
AMD Athlon II X2 215 (Dual Core)
220W Supply...(I know, WTF were they thinking?)
3 GB DDR2
320 GB HDD
and a Nvidia Geforce Integrated 9200

Basically, i got a Dota 2 beta key, and I would like to play the game on on as close to the highest settings as possible. Should I over clock my processor? Is it safe? What GPU should i get after or before overclocking to prevent bottlenecking, because i know the processor kind of blows. Do i have to get a new processor? Any advice would be great.

Thanks, HAPPY NEW YEAR! -Austin

Before you even think about overclocking or a GPU you'll need a new PSU.

That's not the fastest proc out.. I'm not even sure how well it will OC.

But you will need a new PSU before anything.. I'd actually perhaps maybe suggest a rebuild?

New Case, New PSU, New CPU (on the same motherboard.. If it supports an Athlon II, it should support Phenom II as well, so a 955 BE or something along those lines). And then a New GPU..

Buttt that's dependant on budget. What is your budget for your total system upgrade? And where are you located? (US?)

EDIT: Your system looks like it was a pre-built system? Like a dell or HP machine or something? If so; your motherboard will most likely not support any Overclocking at all. What brand/model is your motherboard? (if you're unsure; download CPU-Z and tell us the Mainboard/motherboard info)