
For those using the Hauppauge HD-PVR with a PC (and not an exender which handles playback perfectly anyway) this should offload the CPU and help with visual quality. Even if your like me and your dual-core computer handles the h.264 files well, this is still a good thing as it will allow your CPU's to worry about things other than rendering.
Note: EVR support comes built-in for Vista but to get it in XP you'll need to install .NET 3.5
via Andy VT's Blog