Cpu : E8500, $189 free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115036
Case: Antec nine hundred , $105 free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129021
PSU: Antec 500W, $85 free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16817103940
RAM: Mushkin 4gb (2x2gb) 800mhz, $66 after rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16820146731
GPU: ASUS 4850 512mb, $155 after rebate, no free shipping (you might want to search around if you can find a 4850 with free shipping)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121253
Motherboard: P5Q Pro, $119 after rebate. You can go for the simple P5Q which doesn't support crossfire, for just $1 less. But if you want crossfire you should go for an x38 or x48 motherboard anyway.
P5Q Pro:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131299
P5Q:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131295
HD: Western Digital 640gb. Faster than almost anything, for a low price and huge capacity. $85, free shipping
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136218
If you plan to overclock,
Heatsink: XIGMATEK HDT-S1283, $37, some say it's the best at the moment, should be more than enough for a moderate OC.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233003&Tpk=xigmatek%20s1283
All in all, it's a bit less than $850, leaving you with plenty for a mouse, keyboard and speakers or anything else you may need.
If you don't need those and absolutely have to spend $1000 you might want to look into the ATI HD4870 or GForce GTX260, they have similar performance, however the 4850 is only slightly worse for a lot less $.
Edit: didn't see the other post, should refresh before posting next time. But don't go for crossfire, on this motherboard you will only get x8 crossfire which is not worth it. In fact, it is not worth it either way. You'll get more performance by going for a single better card than a second 4850 on that motherboard.