I've used the Space navigator for years, I can't imagine working without it. About every two months it 'drifts' which is quite annoying. I always get it to work in about ten or twenty minutes, never knowing exactly 'what' fixed it. Uninstall it or repair it, reboot, change the speeds and use the tutorial videos and challenge tests.
When I'm pining for one of the wireless upgrades with all those shortcuts I always wonder it they're prone to setup problems too. For me SketchUp is like a musical instrument, as you get better some routines become automatic. That's when the shortcuts start to make sense, but working in a concentrated manner like that is quite an effort. I take frequent breaks. From Matt Donley's and Nick Sonder's books, I'm slowly learning how to organize things. There are ways to draw 'perfect' geometry resulting in most groups being 'solids' and then using routines to build a house almost as you would in real time, on site. The Space Mouse causes the processor to work harder resulting in more heat, and the fan comes on. That's a limitation for computers with slower processors and 'just' enough memory.
Maybe next year I'll have a Eurocom (everything is upgrade-able) that looks more like a Camaro underneath than a 'puter. Mega horsepower for both motherboard/processor and graphics card/processor, elephant memory and dual everything cooling system. The Cdn$ isn't doing well either, I might have just talked myself into it.