eHomeUpgrade points out that Microsoft has posted a useful compatibility list for its Media Center Edition 2005 product. Since rolling your own system is not supported by Microsoft, it takes some finagling to get an Microsoft mom and pop shop to sell you the software separately (you can also check ebay, but be very careful of scams). TheGreenButton.com is also a good resource for MCE2005 questions and issues.

This compatibility list at least takes some of the guesswork out of building a system.