Updating PC need assistance

[27power]

I want to update my PC so that i can run video capture software (Xsplit) capturing at a decent resolution and quality whilst i play relatively recent games (doesnt have to be on super high quality, im talking about mid quality graphics in game). i am an absolute noob when it comes to hardware and as such have turned to people who would know.
I am currently running
CPU= AMD Phenom(tm) II X4 925 Processor (4cpus), ~ 2.8ghz
GPU= ATI Radeon 4870 2gb
Ram = 3gb DDR3
Motherboard = Gigabyte Technology GA-MA785GMT-UD2h
PS = 750w

I want to keep as low budget as possible.
i should also mention i am on 32bit vista atm so i imagine i will have to upgrade to 64bit 7 to get anything done.

 

[27power]

Sorry just saw the sticky
Purchase Time = 1 month
Budget = as low as possible that can still acheive my goal
Preffered Website = Um theres a parts list on MSY.com.au (http://www.msy.com.au/Parts/PARTS.pdf)
Country = Australia
Overclocking = no. im not good with PC hardware :S
SLI = no
Moniter = HD

 

[hella-d]

Dont Waste Your Money, Max The The RAM, Upgrade To A 64-Bit OS, Switch To Nvidia Graphics (CUDA) Add An SSD And Call It Good, I have A Simular Setup (Until The Parts For My New Build Arrive; AMD FX6100, Dual 150GB Velociraptors RAID-0, 8GB DDR3/1600, Nvidia GTX460 1GB) And I Can Encode A HD 1080P x264 To DVD Format And Burn It In About 15 Minutes All While Multitasking.