How could I improve this $800 Build?

What do you mean by "production"?

Overall you have a good build. The biggest thing I have issue with is the GTS250. When its on mega sale for $50 its a great card. Its ok at $80-90, but much more then that and its bad. At $150 its a rip off as you can get the faster 5770 or GTX450 for $130. (and you get DX11) If your going to spend $!50 on a card, spend $170 instead and get the GTX460. If your going to spend $150 or less, then the 5770 is best, followed by the GTX450.

The AC7FP is not a bad cooler, but something like the Hyper 212+ costs just a little more and has a larger cooling capacity.

Thats what I forgot to mention. Is the 212+ still cheaper on other sites like amazon? They had it for $30 recently.

Don't know. But even at $35 - $40, the improvement in cooling capacity is worth it.

I like the Xig Dark Knight, but I think its price has also gone up since I bought my last one a couple of years ago.

Once your into the $50+ range your better off with one of the TRUE coolers. The Freezer pro type stuff is good $20 units, the 212+ is a good $30 unit, but for $50 the TRUE is a better cooler.

CPU/mobo combo:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
RAM/PSU combo:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
Video card/OS combo:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
Cheaper Case/ODD combo
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

I suggest getting an antec case and 750 antec for $139.99 combo deal for a better price.
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

Take the $20 or so you save and add it to a GTX460. Get free just cause 2 game in the deal.
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

Here is a good deal on a bit better mobo with your CPU.
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

For SLI at full 16x/16x the ASUS M4N98TD EVO AM3 NVIDIA nForce 980a SLI may be a good motherboard for you.
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

I'm guess your hoping for at least one core to unlock. I have to state its possible no cores will unlock and you could be left spending a lot of money on a dual core system.

Also, instead of going for Phenom II X2, why dont you get a Athlon II X3/X4.
You wont get the L3 Cache, but get one (or two for X4) extra cores. That would help in both gaming and productivity without affecting your budget.
Also IMO, HAF 922 seems to be a bit on the higher side for the proposed system. How about an Antec 300 or NZXT Gamma? I'm talking from a value perspective.
Also, AMD CPU systems MAY not be able to take full advantage of DDR3 1600 RAM, unless you overclock everything properly. You might save money by getting a DDR3 1333 RAM (2x2GB), without giving up any performance.

Thanks for the great feedback. I'll take a look and post what modifications I'm considering.

Ok, I've made some adjustments. Just to clarify, I will be using this machine primarily for marketing and design work. I just Photoshop and Illustrator extensively and do occasional video editing. I also want it to play games without to much of a sweat.

Here are the changes I'm now considering:

1) GPU. Switch to the GTX460 for $169.99 (thanks for the free game combo link). When I search for GTX460, there's a huge spread in prices for cards. What are the differences between them?

2) CPU Cooler. The Hyper 212 is actually the same price as the one I had chosen so I'll buy that instead. It sounds like I'm close in price to the next tier of coolers. My question is, is it really necessary or will the Hyper 212 be enough?
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

3) CPU/Mobo
I think I've been sold on changing to the X4 955 CPU and ASUS M4A88TD-V EVO Mobo. It seemed like money well spent investing in a better CPU and with the discount, the Mobo is the same price as the one I had chosen previously.
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

4) PSU - I'm tempted to go with the combo deal elbert recommended. The memory is the same price, but the PSU is much cheaper by $40 (which would just about cover the CPU upgrade). Some of the reviews for this PSU concerned me. Is the savings worth the downgrade?
Here's a link to the other PSU:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

5) I know the case may seem to be a bit much, but I really value quality cases that don't require screws. Maybe there's another screwless case with sufficient ventilation for overclocking that's more affordable.

5) One more question. Do I need to buy any thermal paste, cord extensions, other small stuff?

I'm really loving this system so far. Thanks for the help. With any luck, I'll order tonight.

Sam

Forget about the CPU cooler and get a GTX460 1GB.

You don't need a 750W PSU unless you're adding a second video card. Here's another combo RAM/good case:

http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

1) There are two different 460s, one with 768MBs of ram and one with 1GB. There are also overclocked and ones with different coolers. The 768MB models are slightly slower then the 1GB models due to the lower memory bandwidth, but it for your purposes its nothing to worry about.

2) The 212+ is fine.

3) I would get a quad, which is why I asked about production. If your doing video editing you'll want the quad. Will probably help with PS as well.

4) That PSU is fine. I haven't read the egg reviews on it but actual sites that review PSUs think its fine. I'd trust them over the egg.

5) You should be ok. My 212+ came with a thing of grease. Not the best stuff, but it should be alright. Your motherboard should come with a SATA cable or two. Your case should have any screws you need. You might want to find a good local shop for any last minute things that might pop up but you should be fine.