Re: There seems to be so many hardware problems with Ubuntu software... makes me nerv
The reason there are so many hardware problems is because hardware vendors generally only support Windows.
For laptops, if you want to have a nice working Ubuntu machine with no hassle setting it up at all, I would recommend looking at the vendors that sell pre-installed Ubuntu machines (Dell and System76) and going with one of those. I would also recommend sticking to intel graphics and intel wireless as they are the best supported (graphics and wireless are the source of the majority of problems people have with hardware).
For building a desktop, just ignore the fact that you are going to install Ubuntu on it. Find exactly what you want and then google for "linux thing_you_want", "ubuntu thing_you_want" and "ubunut hardy thing_you_want". That should give you an idea of how well the hardware is supported on Ubuntu and whether it's worth buying.
Don't try to make something "fast" until you are able to quantify "slow".