First Time Builder Seeking Critique on Final Build

[leadpill]

I am on a 700$ budget.(excluding the 100$ for vista 64-bit)

I am just about ready to purchase several parts to this PC, but I needed some help with a few things first. First, I was just wondering,
is all of this hardware compatible, and do I have everything I need for it to run smoothly? Second, I haven't yet decided on just a few
of the parts that I need. I don't know which video card I should get, they are listed below, but all of them seem pretty good (yes I do
realize that both of the radeon cards are the same, but one company might be better than the other, who knows?). I am open to suggestion,
so if you have one just post it. (Although if you do suggest a change or something of the sort, please provide a link to where I can get
the part)

SAMSUNG 22X DVD Burner Black SATA Model

COOLER MASTER Centurion 5 Black Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case

Western Digital Caviar SE WD1600AAJS 160GB 7200 RPM 8MB Cache SATA 3.0Gb/s Hard Drive

CORSAIR CMPSU-550VX 550W ATX12V V2.2 Power Supply

GIGABYTE GA-EP45-DS3L LGA 775 Intel P45 ATX Intel Motherboard

Intel Core 2 Duo E8400 Wolfdale 3.0GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor

G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory

XFX GeForce 9800 GTX(G92) 512MB 256-bit GDDR3 PCI Express 2.0 x16 SLI Supported Video Card
OR
SAPPHIRE 100242L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card
OR
MSI R4850-512M Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card

Microsoft Windows Vista Home Premium SP1 64-bit English for System Builders 1pk DSP OEI DVD

Also, I am a first time builder (I have done a few small changes, such as RAM or a video card, but nothing like this), so if you can, please
post a link to a good guide that can help me put this thing together. Thanks for your help.

 

[Rage_3K_Moiz]

I'd recommend stepping down to this CPU and getting your motherboard from here. Also, step down to this PSU and use the remaining money to upgrade to a GTX 260 or the HD 4870. Both perform on par but the ATI card runs hotter, so if you're worried about whether or not your case is ventilated enough, the GTX 260 is for you.

For a good guide, check this one out.

 

[leadpill]

I'd recommend stepping down to this CPU and getting your motherboard from here. Also, step down to this PSU and use the remaining money to upgrade to a GTX 260 or the HD 4870. Both perform on par but the ATI card runs hotter, so if you're worried about whether or not your case is ventilated enough, the GTX 260 is for you.

For a good guide, check this one out.

I am only buying from NewEgg, I already chose the 8400 instead of the 7200, because the 7200 won't last much longer.

 

[EXCellR8]

The GTX260 is still a waste of money if you ask me. There aren't even that many 3D apps, besides benchmarks, that can take full advantage of that card. Sure, you are future-proofing your system for the next year or two but I think the 9800GTX is still the better buy.