Intel HD Graphics 2000/3000 on Ubuntu is decent nowadays. HDMI is supported, but I don't know how well it can do 1.4a. At least HDMI audio is supposed to be working. But as you might know audio is always the most problematic part of HDMI, no matter what graphics card brand or driver (open- or closed-source) you use, probably except AMD's proprietary driver which seems to have it working right.
About sensors, probably these commands can make it work:
The coretemp module is for measuring the temperature of Intel Core, Core 2, Core i, etc. CPU's and probably their Pentium/Celeron derivatives as well. It works well on Ubuntu Natty so should work on Oneiric as well. As sudo sensors-detect did not yet detect it on some CPU's on Natty you had to load it manually. Oh yes, adding coretemp to /etc/modules makes it permanent.
sudo modprobe coretemp
I don't know if Oneiric has any improvement on this.
If you need a board with out-of-the-box reliable lm-sensors support without needing much terminal work, get an Asus one with AMD CPU (M4N68T LE V2 is a good Linux-compatible board).