HD Sentinel Pro is larger and more expensive than you'd probably want, but I still wanted to recommend it; though it does a lot, the footprint is still small and it is portable. Other than that, of course there is
SpeedFan. I've used both, and they both will do what you want (except for the color change on speedfan).
There was also a thread on Tom's hardware a while ago, and there were several recommendations:
HDDTemp Hardware Sensors MonitorArgus MonitorSensorsView (google it- it was blocked from work as malicious services, so I didn't want to post the link)
I didn't any of them (I used speedfan at the time), but I figured I'd pass the recommendation on.