I7-920/6gb of OCZ Ram (thanks Proximon) Price: $430.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
GIGABYTE GA-EX58-UD3R LGA 1366 Intel X58 ATX Intel Motherboard: $188.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Coolermaster HAF 932 Full tower (the reason for a full tower is for good air flow while allowing for large CPU heatsinks/fans- $139.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Windows 7 Pro 64 Bit/ 1Tb Samsung F3 7200 RPM Internal HDD- $209.98
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
Gigabyte GTX 275 (3% performance boost over standard GTX 285)- $299.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Antec TruePower New TP-750 750W Continuous Power ATX12V V2.3- $114.95 ($20 mail in rebate)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
LG Black Bluray 8x Reader/16x Dvd Burner $99.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Scythe MUGEN-2 SCMG-2000 120mm Sleeve CPU Cooler - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It is over your budget by about $110-$120, but hey it isn't refurbished. I really am not happy with the motherboard, but you are on a tight budget, and require so much. Also this includes Windows 7 Professional 64 bit OEM. I know you also need a Monitor/Keyboard, but that's pushing it as far as getting an I7 system that is not going to castrate the CPU.
Total shipped~ $1,532.50 (and $45 off if you do the mail in rebates)
@Refurbished systems: I think it would be cheaper to use the refurbished system as it is, or atleast pull the parts as needed. The only issue is if they are willing to put warranty on them. Judging by the prices not sure how they could... Second the motherboard most likely is HP's "custom" motherboard (basically meaning it isnt a consumer part) which really puts me to thinking if it's up to par with handling a I7.. Second the memory might be a cheaper brand, or HP only ram which once again makes me thing if it's quality enough to last a long time and handle buffering/caching by video editing..
Conclusion: If it comes with a decent warranty *read the warranty* it might be a good idea to just use the prebuilt refurbished systems over building a new one..