Help me put together a computer build for average gaming

[leadpill924]

Since I think it's about time for me to get a better system, my current one is too crappy to be upgrade due to it being AGP. The current specs on it are

Motherboard
CPU= AMD Athlon 1800+
RAM= 1024mb
Video Card= Radeon 9200
80 GB Hard Drive

Could someone please put together a build that costs under 800$, and can handle source games and multiple other games on high/medium settings with good fps. I'm not looking for top of the line stuff. Just a good duo core processor, a good video card, that won't cost me a fortune. Now I'm not really good at building them, but I'm pretty sure that there are good sites to guide you through it, so I can give it a try, and if not I'll call the Geek Squad or something. Please include all the stuff I need because I don't want to find out that I need additional stuff when all of it arrived and I will have to wait another few days.

 

[leadpill924]

No help yet? I need this bigtme.

 

[Cinders]

What are the specs for your current PSU, hard drive, optical drive, case, monitor, keyboard, mouse, and operating system? And will you be reusing anything?

 

[leadpill924]

What are the specs for your current PSU, hard drive, optical drive, case, monitor, keyboard, mouse, and operating system? And will you be reusing anything?

Nothing worth reusing at all in the actual computer, I can reuse the mouse, keyboard and monitor though. MX518 mouse, original G15 Keyboard, and a 19 inch widescreen monitor with 1440x900 resolution.

PSU is unknown
Hard Drive is 80 GB
Optical Drive is there, but it can burn and read disks, don't know the much details about it
Case is also old and too cheap to bother reusing
Operating system is Windows Xp SP2, build 2600 I think