My viewport seems to have a lot of problems. It's not rotating correctly and a lot of Houdinis features are not working. Basic example is creating a box and adding Cloud rig. The box displays fine but you don't see any cloud in the viewport.
I had amd raedon 6970 HD and thought that was the problem after reinstalling 10+ drivers. So today I bought new 3d card and I have exact same problems.
I'm using Gforce 660 Ti Windows 7 64 bit Build 12.5.376
The viewport rotation could be the preference for ‘Tumbling Method’ - its sounds like you have ‘Classic Houdini Tumbling’ selected under Houdini Preferences/3d Viewport. Try the other options - ‘Standard’ will most likely be familiar. You can also ‘home’ the viewer onto an object by selecting the object and pressing spacebar+G
The rendering quality looks like your settings are too low. Try changing the levels of Transparent Sampling under Out/Mantra node/Properties/Sampling to 10 and also set the Pixel Samples to 6