1.)  First, you'll need to figure out a budget for your gaming pc.  An extremely budgeted gaming pc will be around $400, but look to spend around $500-600 for a decent one.

2.)  Next you will need to decide what necessary components you need, and how much you are willing to spend for them.  Here is a quick guide, but you can  more online about "Budget Gaming PCs".

  * CPU - Gamers usually prefer the AMD Athlon 64 Processor because of it's price to performance ratio in comparison to Intel CPUs and its overclockability.  For a budget gaming pc we will need an AMD Athlon 64 Processor, either the 754($) or 939($$$).

  * Motherboard - There are hundreds of different motherboards to choose from.     For our purposes, we will look for either the socket 754($) or a socket 939($$$).  Make sure you get a processor to match your motherboard socket.  It all depends on your budget.  We also want a motherboard that supports SATA.  We'll need to consider what video card you want the motherboard to support either an older AGP slot($) or the PCI-Express slot($$$).  

  * RAM - The standard memory these days is 512mb minimum.  If you have the extra budget, you'll want to spend it on RAM first.  If you decide to go with a socket 939 processor, look to buy identical sticks of RAM amounting to 512gb or 1gb to take advantage of the dual channel architecture.

  * Hard Drive - A 40gb SATA hard drive is plenty for a dedicated budget gaming pc. If you absolutely need the space, then I suppose you could go 80gb.  (But keep in mind, this is for a BUDGET gaming pc.)

  * DVD-Rom - To keep costs to a minimum, you'll only need a dvd-rom.

  * Power supply and case -  There are thousands of power supply and case combos out there.  Basically all you'll need to look for is a standard ATX case with a power supply minimum of 350W.  (Antec cases/powersupplies are one of the best)

  And most importantly,

  * the Video Card  -  We could go into an entirely different guide in this section, so for simplicity purposes we'll break it down to the low range agp and mid range pci-express cards from ATI and nVidia.  Low budget AGP: Nvidia FX5200 or 6200, ATI 9250 or 9500.  Mid range PCI-E: Nvidia 6600 or ATI X700/X800.  There are many different brands and different speeds that each model usually runs at.  For nvidia cards you can trust on XFX or eVga cards, and for ATI you can trust in the ATI brand or Sapphire brand cards.

 

 

3.)  So ultimately we can break it down to the Ultra Budget PC and the Budget PC.

 Ultra Budget PC
---------------
"socket 754" Athlon 64 CPU
754 Socket Motherboard w/ AGP & SATA
512mb RAM PC3200 DDR400
40gb SATA Hard Drive
DVD-Rom
Case & 350W Power supply
AGP FX5200 or 6200, ATI 9250 or 9500

 

Budget PC
---------
"socket 939" Athlon 64 CPU
939 Socket Motherboard w/ PCI-Express & SATA
1gb(2x512mb) RAM PC3200 DDR400
80gb SATA Hard Drive
DVD-Rom
Case & 350W Power supply
PCI-E Nvidia 6600 or ATI X700/X800

 

4.)  To search for these components, browse to each respective part's category.  For instance for the Athlon 64, you will click: on Buy on ebay's front page and follow these categories:

Computers & Networking
=>Desktop PC Components
=>CPUs for Desktop PC
=>AMD
=>Athlon 64

and then specify your search with "socket 939" or "socket 754".

5.)  Do this for all the perspective computer parts, and purchase the parts, and you'll have yourself a budget gaming computer good enough to run the late generation games such as World of Warcraft, Counterstrike: Source, Wolfenstein: Enemy Territory, and more!

 

Have fun, and good luck!