Approximate Purchase Date: no rush, but preferably within several months
Budget Range: flexible, $600-$1,000
System Usage from Most to Least Important: mainly gaming, also video editing
Parts Not Required: monitor, keyboard, mouse, speakers, hard drives - possibly power supply, CD/DVD drive (unfortunately unsure of the power supply, bought it in a store a few years ago when my old one died so no online record, can look it up later though)
Preferred Website(s) for Parts: newegg, but open to other sites
Country of Origin: USA
Parts Preferences: none as long as they're reliable
Overclocking: probably not
SLI or Crossfire: not even sure what this means...
Monitor Resolution: 1024x768
Additional Comments: I originally built this PC 5ish years ago, and have made miscellaneous upgrades. I understand the general concept, and would rank myself a 2 or 3 out of 5, in terms of experience/knowledge. I'd like to be able to play games such as BF3 on high settings, and hopefully have a machine that will last me a few years without needing to upgrade again.
I can reuse the same case, but if not, I'd prefer something relatively quiet without worrying about my computer overheating. Space for several card slots (i.e. graphics, broadband modem, etc) and hard drives is a plus too, and something that won't necessarily take an engineering degree to assemble.
The PSU and motherboard will allow you to add another 6870 in crossfire later on if you wish to. You could fit into budget a better GPU but its probably overkill at your resolution.
With $250 left over:
It might be worth using the remainder of your budget getting a 1080p monitor (1920x1080) and switching the 6870 graphics card for a GTX 560Ti or 6950. Just an idea, but its worth your consideration
The only thing i would change is the PSU. You can get away with 500 to 600 watts since it won't be a power hungry rig. Get a 600 watts. Cheaper
I wouldn't want to run Crossfire 6870's on a 600w PSU, and certainly not a 500w. A single card maybe, but then you may as well buy a cheaper motherboard as well that isn't crossfire ready for like $80.
With your budget, you can do very well. Here are some of my ideas:
1) The 2500K is the cpu of choice for gamers. 4 cores is more than you need, and it will overclock easily past 4.0. That is what the"K" is built for. About $200. Less if you can pick one up at a microcenter.
2) The graphics card is the real engine for gaming. Spend your budget here. Something like a GTX560 or 6870 will be about $150. If you have the budget, go higher up to a GTX570 or 6970 for gaming.
3) Get a Z68 motherboard. That will allow you the ability to use the integrated graphics of the 2500K to aid in video editing. I am no expert there, do some research on "quick sync" You might look at micro-ATX motherboards which have only 4 expansion slots. They are cheaper, but will not run multiple graphics cards well.
4) 8gb of ram is a good number, get a 2 x 4gb kit. Speed specs are unimportant. Don't pay extra for high speeds or fancy heat spreaders. DDR31600 is about as high as you need to go.
6) A psu of 600w will power any card up to a GTX580. Just get a quality unit. My short list of quality units would include Corsair, PC P&C, Antec, Seasonic, and XFX. Your currrent psu is a cheap 450w unit with only 18a, not enough for today's gaming systems. Here is a list of what some graphics cards require:
GTX550ti needs 400w with 24a on the 12v rails plus one 6-pin PCI-E power lead.
GTX560 needs 450w with 24a on the 12v rails plus two 6-pin PCI-E power leads.
GTX560Ti needs 500w with 30a on the 12v rails plus two 6-pin PCI-E power leads.
GTX570 needs 550w with 38a on the 12v rails plus two 6-pin PCI-E power leads.
GTX580 needs 600w with 42a on the 12v rails plus one 6-pin and one 8-pin PCI-E power lead.
GTX590 needs 700w with 50a on the 12v rails plus two 8-pin PCI-E power leads or 4 6-pin power leads.
7) You probably want to get a DVD burner. They are only about $20. I have used Samsung and ASUS which are ok.
8) At 1024 x 768, you do not need the strongest graphics card. But, consider adding a 22-24" 1080P monitor. You will see more of your game and have more desktop real estate for other uses. Do keep your old monitor if you have the desk space. I find it useful to keep e-mail and monitors open while gaming. It adds no appreciable load to the gaming card.
9) Windows-7 home premium 64 bit is the os of choice.
10) Plan for an aftermarket cooler. It will keep your pc quieter under load, and will let you OC higher and easier. No need to pay much. $30 gets you a CM hyper212 or a Xigmatek gaia cooler. Paying more gets you only marginal improvements.