A while back I moved my HTPC to Windows 7 so I thought I would do a quick write-up of the experience. I wasn't unhappy with Vista, it was running well, but I had done a W7 install on a media centre I built for my brother and I was impressed with some of the new features (dragable timeline, red button support, support for more than two tuners). I had a slight issue with the upgrade where I managed to wipe out 1Tb of ripped DVD images (which I thankfully have on physical disks), in retrospect I think that was my fault rather than the installers (I blamed it initially).
As before I installed Astrotoy7's black theme (I used Media Center Studio to install) and the latest beta of Mediabrowser.
As with Vista I installed the codec pack from Shark007.net (obviously picking the Win 7 version this time).
The installation wasn't pain free, however. After installing I found that my TV tuner kept giving me an error about no tuners being available, despite the fact that none of them were being used. Thankfully it wasn't affecting recorded programs (it did initially, it did improve after some tweaking). Initially I assumed it was the Hauppauge tuner drivers and Win 7 but I tried installing the latest drivers and no joy. In the end I tracked the answer down to a Green Button forum post (I had seen others to be fair) which suggested it wasn't the tuner but the graphics card, the onboard ATI HD3200, more specifically the catalyst control centre it comes with. I had the latest drivers but these don't help, I had to downgrade to the 9.8 drivers and low-and-behold that seems to have sorted it and I now have a fully reliable HTPC back. The new drivers also seem to have sorted some other reliability issues that meant random freezing and reboots.
Another issue I had, which seems to have sorted itself too (after the graphics upgrade, though it could have been a Windows Update fix), was connecting to the network after waking, for some reason no matter what I did it only found it as a public network rather than my home network, so wouldn't connect to the internet.
All in all not a great changeover, normally I follow the old rule of "don't install a new MS OS until the first service pack has been released." I thought Windows 7 was a service pack for Vista, so went ahead, probably not the wisest choice on reflection. Maybe it doesn't need the service pack anymore, but certainly give it couple of months to bed in. The ordeal is over now though and everything is running smoothly again, I hope.