Mr. Wood,
I am in a bit of the same situation except that I will be using complex models and will be rendering using SU Podium. If you don't find the information that you need here, you might try a sub on Reddit called Build Me a PC https://www.reddit.com/r/buildapcforme/
This is for those who are looking to buy the components individually and build their own PC, which could result in significant savings not to mention the ability to customize your machine to your specific purposes. One thing I have read is that SketchUp does not take advantage of multiple cores so you might take that into consideration when choosing a computer/chipset. Good luck with your search!