Media Center PC

I have an older HP Pavilion 9500 series with a core 2 quad processor (2.5G). I'd like to upgrade my processor from the NVIDIA 9200. What is the best single slot GPU available for such a system? Also if so inclined, what would be a good processor upgrade for this 11 yr old system. Yes old...

I have a Home Theater PC in my living room that's designed to hold my entire media library, and stream games off my Gaming PC from upatairs. Its built out of my spare parts, and one of those is an old case with almost no airflow or proper ventilation, and my CPU runs at 75°-80° when doing...