New gaming build

Hello
I new to the forum and trying to get some help on building a new gaming computer. I have not built a computer since the 486 days.I have bought computer since then but the last one was in 2001.
I plan on playing mostly RTS and some FPS. So I am looking for some thing that can do both but not looking for blazing speeds. I am willing to spend up to $1200.

The motherboard that I have picked is the
GIGABYTE GA-EP45-UD3P .

The CPU is a Intel Core 2 Duo E8400 Wolfdale 3.0GHz.

The case that I am like is a coolmaster with this power supply.
COOLER MASTER RC-690-KKN1-GP Black SECC/ ABS ATX Mid Tower

COOLER MASTER UCP RS700-AAAAA3 700W ATX12V / EPS12V SLI Certified CrossFire Ready 80 PLUS SILVER Certified Power Supply

hard drive
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s

The only questions that I have is
This is the ram that I have picked

CORSAIR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel

The video card is all new to me
ATi or nvidia I do not know

Thanks for the help.

Don't take Slaytharn's comment into consideration (except for the part where he says it'll be all right).

DDR2 comes usually either in 800 or 1066mhz and that is "stock" speeds. You can overclock and whatnot.

DDR3 is a whole different beast and apparently, slaytharn mixes them together in his head

slaytharn is on the wrong track .

For video card have a look at this site
http://www.guru3d.com/category/vga_charts/

These were done with a similar computer to your build .

30 fps is playable . Buy the gfx card you can afford , for the games you are likely to play at the resolution of your monitor .

http://www.newegg.com/Product/Prod [...] 6814127392 $154.99 ($134.99 after $20.00 Mail-In Rebate)
MSI N9800GTX Plus-512M OC GeForce 9800 GTX+ 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail

+1 on the Gigabyte mobo.

CPU: if you want to save a little cash, go with the E7500 or E7400.

+1 on the Coolermaster CM-690 case.

PSU: Get either the Corsair 750TX or the PCP&C Silencer 750 (the red one is the best deal). I wouldn't go with the Coolermaster PSU and you should have a 750W size.

+1 on the Caviar Black 640GB

RAM: Get 2x2GB of G.Skill Pi Black DDR2-800. It's the best value for gaming.

Video Card: Get the Sapphire 4870 1GB card, which you can then Crossfire in the future. Don't use a nVidia card on that mobo, because you can't double it up in the future.

You'll need a heatsink as well--Xigmatek HDT-S1283 w/ retention bracket and MX-2 thermal paste. Overclocking the CPU will help for RTS and FPS games.