Building a workstation/htpc...advice on parts?

[Gamehendge Jazz]

Building a system for everyday app usage, audio/video editing, mid-level games, audio playback & a dvr. Comments on any/all parts will be much appreciated...

Motherboard: ?

Memory: My current 512 is FAR from sufficient for my audio/video editing. Looking at getting 2GB DDR2. Any recs on make/models?

Hard Drives: Thinking Western Digital 74GB Raptor as main. Maybe a couple SATAII 250's for storage and DVR.

Video Card: Leaning towards a Geforce 6800, but not sure which manufacturer/model to choose.

Power Supply: I hear of more people exerperiencing problems with various system components due to an insufficient power supply. A quiet and reliable PS would be nice.

[Gamehendge Jazz]

Here's a start...(any comments?)

Case: Lian Li PC-6070B (http://www.lian-li.com/Product/Chassis/M_C_S_PC-6070.htm)
Power Supply: Enermax Coolergiant EG485AX-VHB ATX 12V 480W (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=100681)
Motherboard: Asus P5GD2 Deluxe 915P Audio/GB-LAB/USB/IEEE/PCI-E/SATA/DDR2-533/800-FSB/ATX Intel P4 775 (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=110205)
CPU: Intel P4 640 3.2GHz LGA775 2MB 800 FSB (HT) (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=120315)
Memory: [2GB] 4 x 512 Corsair TWIN2X1024-5400C4 ($185/pair)
Main HDD: Western Digital 74 GB SATA 10K Raptor (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=150239)
Storage HDD: 3 x 320 - Western Digital 320GB SATA 8MB Cache 7200RPM (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=150439)
Video Card: eVGA GeForce 6800 256mb 256bitDDR/PCI-E/HDTV/DVI (http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=190676)

Should there be concerns for overheating this case? I prefer the mid-tower case.
Enough/too much power?
Motherboard/memory?