Need Advise on final Heatsink - Power Supply - MOBO Selection

I am a novice, this is my first build. Main use will be HTPC (music and movies), some video and photo editing. Have configured the build, but need advise on final power supply selection and the heatsink. (My CPU came without the heatsink and fan) Also, welcome any feedback on the MOBO selection (the MA785GPMT versus MA785GMT that does not have the side port, read accounts of issues with the GPMT audio?)

1- Is the HSF the right choice for an AMD X4 805 CPU and will I need to also purchase the thermal compound (description seems to indicate the HSF comes with the thermal paste already applied)
[url=HSF: http://www.newegg.com/Product/Prod [...] 6835186030 ][/url]
$19 ACALP64PWM Arctic Cooling

2- The Corsair 650 and 550 version power supplies are currently the same price, any downside in terms of cooling or on the electric bill using the higher wattage option? (If the MOBO isn't adequate for video, will add a discrete card later on)

Proposed System Build
GIGABYTE GA-MA785GPMT-UD2H AM3 AMD 785G HDMI Micro ATX AMD Motherboard - Retail

COOLER MASTER Elite 360 RC-360-KKN1-GP Black Steel / Plastic ATX Mini Tower Computer Case - Retail

CORSAIR CMPSU-650TX 650W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC - Retail

SAMSUNG Spinpoint F1 HD753LJ 750GB 7200 RPM SATA 3.0Gb/s 3.5" Hard Drive - OEM

ARCTIC COOLING ACALP64PWM Fluid Dynamic Cost-Effective Ultra Quiet AMD CPU Cooler - Retail

Existing 47" 1080p LCD, Wireless Keyboard, Mouse and DVD/CD Combo

Microsoft Windows 7 Home Premium 64-bit 1-Pack for System Builders - OEM

dark_lord69
Thank you for the quick reply. I hope to order everything today and wasn't sure about these items. Two final questions
1- Any advise on the MOBO? I am inclined to think that there is not much difference between the GPMT and GMT versions of the Gigabyte board other than the extra video ram. However, on egghead many have commented on audio issues with the GPMT version. Any insight?
2- Some have advised that I should use the AMD X3 720 instead- that I will see better performance at a lower cost. Would this be a better choice for my application / while maintaining an energy efficient system? (I thought 4 cores would be better, but understand the 720 is 2.8 rather than 2.5)

Thanks again.