Please assess my HTPC machine

[Max-Powers]

This is a HTPC that will be doing everything a HTPC does plus some decent gaming. This will be on a 42''+ LCD 1080p. The cost for everything on Newegg is around $1200. I will order the parts the first week of July, so it may change very slightly by then. I will also search for better prices. For now, everything can be gotten at newegg. I will do some overclocking

Operating System: Vista 64? I hear I need Vista 64 to be able to use 4GB ram, but some say Vista 64 is horrible. Should I just get it anyway?

Case: Silverstone LC20B

Motherboard: Gigabyte GA-MA790X UD4P

CPU: Phenom II X3 720 BE

CPU Cooler: Noctua NH-U9B (This may change)

Video Card: ASUS HD 4870

RAM: Corsair 4GB (2x 2GB) DDR2 800

Power Supply: CORSAIR CMPSU-650TX 650W

Hard Drive 1 WD 500 Gig

Hard Drive 2WD 1.5 TB

Blue-Ray DriveLITE-ON BD/HDDVD combo drive

Remote: Gyration Air Music Remote

What is some software that I would need to buy? Please tell me what you think and if there will be any compatibility issues that you see. I am fairly sure it has enough power to do what I want, but do you see anything that may be better or cheaper or unnecessary?

Sound System: Energy RC-10 fronts, Energy RC-mini center, Energy C-100 surrounds. Denon 1909 AVR.

 

[Dangman]

Your RAM and GPU are the same exact link.

 

[engiNURD]

HTPC without a tuner?

 

[Dangman]

Operating System: Vista 64? I hear I need Vista 64 to be able to use 4GB ram, but some say Vista 64 is horrible. Should I just get it anyway?

For HTPC use, any 64bit OS sucks for HTPC use. Codec issue, mainly related to DXVA, is the main reason why 64bit OSes aren't recommended for HTPC use, judging from the general thoughts in the HTPC subforum. Example:
http://www.hardforum.com/showthread.php?t=1415560

What is some software that I would need to buy?

Hit up this guide and check out CoreAVC Pro:
http://www.hardforum.com/showthread.php?t=1276654

Do you actually need an ATX setup? Do you actually need that much expansion room? Do you actually need to be able to game on this HTPC?

Oh and for the exact same price as the HD4870 512MB, you can get the faster GTX 260 with free shipping:
$170 - BFG Tech BFGEGTX260896OCE GeForce GTX 260 896MB PCI-E Video Card

 

[Max-Powers]

HTPC without a tuner?

I will get a tuner later when I figure out more about what cable company I want to go with and what they offer. I am deployed right now and will go back to Lawton, OK next month.

 

[Adidas4275]

the ATI 4770 would definately fit your needs and is a great $100ish