I just completed my HTPC last night. It has the new Wolfdale Pentium E6300 Dual Core. My old PC was a P4 3.0ghz and this was my first multi-core CPU. I am very pleased with this CPU, plus, it was only $15 more than the P4 chip I bought last, but is so much faster. If the Q9550 or Q9660 is still around next year or the year after, I'm going to pick up one of those. Right now, I can't justify paying $215+ for the Q9550 and over $300 for the Q9660 knowing that they price will drop drastically soon. The E6300 is easily overclockable to 3.4ghz and only costs $82.
I was comparing the playback of Windows 7 Media Player vs VLC 1.0.1 and it was simply amazing have two 720p videos playing side by side without so much of a hiccup (like the P4 playing just 1 720p video).
Here's the video I used: Link Removed due to 404 Error