If you acquire a Desktop PC unbundled - can be difficult without a self build, or a few shops that specialise in that, then you can save the cost of Windows. Some such shops may even do the initial Linux install for a fee - actually most of them USE the Linux utils on the Linux boot disk to sort out the HW, and even do a 'live install boot' nowadays just to do a quick check anyway. :-)

All new laptops seem to come bundled, except from a few special suppliers who (not talking about Dell!) can provide a fully setup system - they provide a service of making sure that the hardware and drivers are all properly setup with Linux - Usually Ubuntu these days - I know that there are a few around from the ads in some very limited specialised magazines (high level security and anti-hacking penetration) I get from time to time.

If as you say it looks like Windows is not 'needed' then the setting up of the HW/SW 'is a good exercise for the student' ... :-)

The only point really worth noting for the (your) pocket book is that the VERY latest hardware MAY have a few minor driver hassles for Linux, but you can end up in that nightmare with just trying to get printers, etc to work too... :-)

"Son is not happy that I've been doing this research"

Haha! Tough! Tell him that the research is ALSO (he's not the centre of the Universe - might be centre of YOUR universe for the moment - :-) - won't hurt the teenage ego to learn that there are things HE never thought of!) for 'self education' !!!! You need to buy new systems for yourself occasionally, too, you know! :-)