How about this? SSD is optional, but would provide almost instantaneous boot. I know I'd hate waiting 2-3 minutes for the system to boot so I can watch TV! Could use sleep mode and the HDD only, too. I used a laptop drive because they are quiet and low power.
PCPartPicker part list:
http://pcpartpicker.com/p/Hb8z
Price breakdown by merchant: http://pcpartpicker.com/p/Hb8z/by_merchant/
Benchmarks: http://pcpartpicker.com/p/Hb8z/benchmarks/
CPU: Intel Celeron G1610 2.6GHz Dual-Core Processor ($39.99 @ Microcenter)
Motherboard: ASRock B75 PRO3-M Micro ATX LGA1155 Motherboard ($76.98 @ SuperBiiz)
Memory: Crucial 4GB (2 x 2GB) DDR3-1333 Memory ($24.98 @ Outlet PC)
Storage: Western Digital Scorpio Blue 1TB 2.5" 5400RPM Internal Hard Drive ($81.68 @ SuperBiiz)
Storage: Samsung 840 Series 120GB 2.5" Solid State Disk ($92.99 @ Adorama)
Video Card: Sapphire Radeon HD 6450 1GB Video Card ($29.99 @ Newegg)
Case: Silverstone ML03B HTPC Case ($54.99 @ Amazon)
Power Supply: Antec EarthWatts Green 380W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($39.99 @ Newegg)
Optical Drive: Asus BC-12B1ST/BLK/B/AS Blu-Ray Reader, DVD/CD Writer ($56.23 @ Amazon)
Total: $497.82
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-03-03 03:44 EST-0500)