Help with building new pc

Hi. I'm planning on purchasing the following components for my new computer:

Intel Core i7-920 2.66GHz

Gigabyte NVIDIA GeForce GTX 260

Corsair DDR3 3GB 15000/1866 (3x XMS3 1GB)

Asus P6T-SE Intel Mainboard

Seagate Barracuda 320GB 7200RPM 16MB SATA 1.5Gbs

Pioneer DVR-217 SATA DVD Re-Writer (20x - Black)

Corsair HX-620 620W ATX Modular Power Supply

Cooler Master RC-690 Black Tower Case


I'm upgrading from this

Intel Core 2 Duo E6750 2.66GHz

Gigabyte GA-P35-S3

4 GB DDR2 RAM 1066/800 (4 x 1GB)

Gigabyte NVIDIA GeForce 8600 GT

Seagatee 320GB 7200RPM 16MB SATA 1.5Gbs

Pioneer 112 DVD-RW

ATX 908 Case


I was just wondering if the system I'm upgrading to is a good idea and if so, how much do you think I could get for my old system (no monitor or peripherals included)?

Thanks