Input on my new pc build / choice

I am on a tight budget of $318 and cannot go over this right now, that said here is my situation. I currently own a very very old gaming rig, its current specs are
CPU: am2 3800+ dual core overclocked to 2.4ghz
Ram: 4gbs of ram ddr2 800 ( 4 x 1gb sticks of ocz gold)
Gpu: HIS Radeon 5670 1gb model overclocked
HDD: 2 80gb 7200rpm drives in raid 0 with a 1tb drive for storage
OS: Windows 7
Power Supply: 650wat
Now my problem is this, i live an hours drive from microcenter i have put together a build with the following,
I will also be purchasing battelfield 3 in this budget
CPU: intel core i3 2100
http://www.microcenter.com/single_product_results.phtml?product_id=0359809
Motherboard: Asus z68 GA-Z68AP-D3
http://www.microcenter.com/single_product_results.phtml?product_id=0375352
Ram: 4gbs of ddr3 1066 ( 2 x 2gb sticks)
http://www.microcenter.com/single_product_results.phtml?product_id=0364398
Im planing to reuse my power supply as its perfectly fine and more than enough for what i need, i will also be reusing my current case and hard drives.
My conflicting issue is this, would it be worth it for me to buy these parts and reuse my current gpu and stuff like that for gaming on at 1440×900? I can get an xbox 360 and battlefield 3 for around $210 or so. Im really on the fence about which one to buy, i have always loved pc gaming but i just cant decide here.
Your input is very looked foreword too, im going to be buying either the computer parts or the 360 in the mourning so any help you could give me on deciding is very much appreciated.
Answer #1
If you’re going to upgrade, do it right. Get a motherboard that is upgradable and cheap. ASRock with USB3, SATA3, and PCIE3 as well as 1Gb LAN. Also, get good RAM, 8GB of 1600MHz RAM in 2x4GB configuration.
Grab these parts from Microcenter.
http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=16928672

EDIT: Prepare for the future man, get better parts for the same price.
Answer #2
upgrading your PC will allow you to play your current games at higher settings if that matters
for the price those parts look good and should give you a decent bump in speed
but your video card will be a limiting factor