HTPC/DVR Build Recommendations

I'm going to be building an HTPC/DVR system in the next couple of months and wanted to get some recommendations. Thanks.

Approximate Purchase Date: Feb 2011
Budget Range: 600-800
System Usage from Most to Least Important: DVR system with MythTV, HD media playback (ripped and physical), Streaming (e.g., Hulu)
Parts Not Required: Monitor & OS
Preferred Website(s) for Parts: Newegg and maybe Amazon
Country of Origin: USA
Parts Preferences: None, but Linux compatibility will be important
Overclocking: No
SLI or Crossfire: No
Monitor Resolution: 1920x1080

Additional Comments: I'm also planning on buying a SiliconDust HDHomeRun Prime once they become available (~$250, which I'm not including in the HTPC budget). Obviously I'd like the system to be quiet, but I'm more concerned with performance; I plan on using it for transcoding, commflagging, and full HD playback (not just transcoded and downsampled files).


Parts:
CPU: Intel Core i3-550 Clarkdale 3.2GHz LGA 1156 73W Dual-Core Desktop Processor BX80616I3550
MOBO: ASRock H55M/USB3 R2.0 LGA 1156 Intel H55 HDMI USB 3.0 Micro ATX Intel Motherboard
or
ASUS P7H55-M PRO LGA 1156 Intel H55 HDMI Micro ATX Intel Motherboard
RAM: G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
GPU: ASUS ENGT430/DI/1GD3(LP) GeForce GT 430 (Fermi) 1GB 128-bit DDR3 PCI Express 2.0 x16
PSU: Antec BP550 Plus 550W Continuous Power ATX12V
HDD: Western Digital Caviar Green WD20EARS 2TB SATA 3.0Gb/s
DVD: LITE-ON Black 4X Blu-ray Disc Reader SATA Model iHOS104-08
Case: SILVERSTONE Black 8.0mm aluminum front panel, 0.8mm SECC body GRANDIA GD04B Micro ATX
or
nMEDIAPC Black Aluminum / Acrylic / Steel HTPC 5000B Micro ATX
Keyboard: Logitech Cordless MediaBoard Pro for PS3
Other: cirago BTA-3210 USB 2.0 (BT dongle for the Keyboard)
Other: HDHomerun Prime (3 tuner CableCard)


All together it's about $700-750 (excluding the tuner) depending on rebates and which combo of MOBO/Case I go with.

My main concern/question is whether or not I need the GPU. If this were strictly for media playback I'd go without it. However, since I'm planning on running MythTV and doing transcoding and commflagging, I'm wondering if I need the GPU in order to offload some of the HD playback (e.g., VDPAU).

I'm not planning on getting anything for a couple of months; mainly I wanted to get a baseline set and then add/trim components from there and watch for deals on Newegg.

Thanks for the help.

Go For the silverstone Case