bryan240g :
CPU Cooler: Scythe SCMNJ-1000 80mm Sleeve "NINJA MINI" CPU Cooler
$34.99
HDD: Seagate Barracuda 7200.11 ST31000340AS 1TB 7200 RPM SATA 3.0Gb/s Hard Drive $189.99
I'd get two WD6400AAKS for a total of $180 and 1280 GB.
You're not going to overclock the CPU in a HTPC, are you? That's kind of rare, you know...
Maybe you don't need that cooler after all.
You'll need a TV tuner. Good ones have hardware encoding, so the CPu is not really used and can be very weak without causing problems. For example my Dad has a X2 5000+ (not overclocked) and a Hauppauge PVR-150 and an ATI Theater 650. Even when both tuners are working at the same time, the CPU is still nowhere near 100%.
I have no idea about HD tuners, unfortunately.
On the other hand, if you intend to do lots of video editing (say, removing ads, converting to DivX, etc.) consider a Phenom quad CPU.