jimmy_dog :
CPU Intel Celeron G530 (Sandy Bridge): 2.4 GHz, 2 MB Shared L3Cache$50
CPU Cooler Intel boxed heat sink/fan 0
Motherboard Gigabyte GA-H61MA-D3V: LGA 1155, Intel H61 Express $60
RAM Pareema 4 GB (2 x 2 GB) DDR3-1333 MD313C80809L2 $20
Graphics Nvidia GeForce 7800 GT $80
Hard Drive None $0
Case Rosewill R101-P-BK MicroATX Mid Tower $30
Power Antec VP-450 450 W $38
Optical LG 22x DVD Burner SATA Model GH22NS90B-OEM $17
$295 total. You could get a Pentium G860 for $50 more. Also there are only 9 7800 GTs left on amazon.
OP, this is an ass-terrible build. Please understand if your pursue building something like this it is BAD, and you are going to HATE it in 3-6 months when more games come out and it can't handle them.
I am probably wasting my breath here, but I'm going to try:
You cannot build a gaming computer for $200, $300 or really even $400. If you spend $300 now putting together that POS build above you WON'T be happy with the results (it is a POS and it will play games like a POS) and in 3-6 months you're going to be exactly where you are today: stuck with a rig that can't do the job. You will have wasted $300 and have to start all over.
What you need to do is save your money so you can buy something that has a little room to grow. If you get into the $500-$600 budget range you can make smart choices that will allow you to maximize your investment.
If you want it TODAY and MUST HAVE IT TODAY you are going to get stuck with garbage and you WILL regret it.
If you can bring yourself to wait and save your pennies you WILL be MUCH HAPPIER!
If you want to get started today and CANNOT WAIT, I suggest you either consider buying USED parts (considerable risk) or go ahead and buy parts that will see you through multiple rigs.
You can go ahead and buy the CD/DVD drive. I still use one from 8 years ago.
You can go ahead and invest in a good case. A good ATX mid or full tower will last you for years. $100-$200 for a case? Sure, but it's the last case you will ever buy. You do not want to put expensive parts in a crappy case where they will get hot and dusty. You want a good case.
You can go ahead and get the harddrive(s)
You can go ahead and buy the PSU- buy a GOOD brand, and a good wattage (500W-750W will see you through for a while yet) Pony up the extra $20-$30 for quality and wattage, because you could easily be using it 3-5 years. It might seem like more NOW, but a crappy or underpowered PSUs just has to get replaced. So you can buy 2 crappy PSUs for $100 ($50 x 2) or 1 good one for $75. Do the math.
These four parts will last you for a long time assuming they don't fail or break, so go ahead and invest in quality right now.
Things you SHOULD NOT BUY first, as they will "age" the fastest:
CPU
GPU
Mobo
RAM (because it has to be paired with the mobo)
There. I'm done. Hopefully you'll see all the parts you can afford right now are nothing you'd keep long term and you'll just end up spending more money long-term. You will SAVE money by doing things "right" the first time and having some patience.
Good luck!