Windows Media Center Edition and Vista

If you decide to use Media Center as your HTPC brain, then you will likely have no need for additional software.  There are few limitations when using MCE, but those are eclipsed by the positive features including the all-in-one feel of the complete interface.  

The main  limitations are that MCE compatibility requires a set of drivers known as BDA.  The hardware you want to use must have BDA drivers, otherwise it will not work with MCE.  

There is also an issue with file playback over a network, or rather limitations to where trusted devices that can be used over a network.  

Finally, MCE does not yet support QAM tuning used by almost all cable companies for digital and HDTV tuning.  

MCE compatible products

TV Tuner cards

Hauppauge WinTV-PVR

HDTV Tuner cards

Fusion HDTV 5 Gold
Fusion HDTV 5 Lite
Fusion HDTV USB
V-Box Cat's Eye PCI MCE Version
V-Box Cat's Eye USB MCE Version

PC Remote Controls

Microsoft MCE Remote