Need advice on upgrading system for gaming!!!

Need Advice!! I just read the following article on Tom's Hardware about upgrading to a budget gaming system:
http://www.tomshardware.com/2005/10/14/the_/index.html

Here's my current system:

- Intel 2.8ghz HT
- Asus P4P800-VM motherboard with Intel 865G chipset, AGP only and SATA up to 150gb/s
- 2x256 ddr3200 and 1x512mb ddr3200 ram for a total of 1 gig
- WD standart 40gb ata drive
- A Open GeForce 6200 256mb vido card

Can I upgrade my motherboard to a better chipset and PCIe without having to buy a new processor?
What basic value upgrade will make the biggest difference in gaming performace for me?

Thanks you in advance for your time and advice!!!

- Gunz

Thanks for responding!!

My budget is 500.00 and less. I want to keep as much of my existing system as possible, but I realize that some things need to go such as the mother board that has no PCIe. What budget motherboard do you recommend that will be able to use my existing processor?

i have to agree with prozac
if you want to keep most of your current sys.

then a video card and memory would be best

EDIT; agp and pci-e with the same video card= not much
or hardly no diff in gaming.

plz do not buy anything more for us system, unless ur desperate upgrading ur current is a really bad idea, save up for a new dx10 system

Directx10 comes out in a few months.

He'd hafta buy a new video card, a new mobo, probably new ram, and a new power supply.

He'd be spending $1200 at least.

It may be better to get something like this... Either that, or save up for awhile (sorry, don't know how much you make)