retrocomputing

Some of the best keyboards ever made, many of them beige, use a 5-pin AT connector. These can be trivially converted to a PS/2 (not P/S2) port with a small adapter.

You might want to browse some mechanical or vintage keyboard forums to see specific models that other people use.

https://deskthority.net/

https://geekhack.org/

You can find native PS/2 mice (like the Logitech First Mouse) on auction sites, sometimes even in new condition. I have also seen adapters for plugging USB mice into PS/2 ports, although I don't know if they work with every model.

The best one is the one you can obtain easily tbh. Old mechanical keyboards from back then are usually pretty good, but looking for a specific model is usually hard.

• keyboard: IBM Model M
• mouse: Microsoft IntelliMouse Explorer

As far as I remember, the Logitech MX518 was one of the best PS/2 mice - but it's not beige, so it might be more appropriate for an XP build.

There are buckling spring Model M and M2 keyboards that will use PS/2 or the easily converted AT. Also look for Focus boards (Alps white) or various Cherry boards (usually Cherry black) with either of those connectors. Hell, I’ve been trying to offload a Tai Hao with Alps clones and an AT plug for a while now.

Quality of boards takes a nose dive once they start coming with “Win” keys, but you can find decent ones even with that. Gotta be more careful if you want anything other than a run of the mill rubber dome though.

If you want new, you could try to contact Unicomp at pckeyboard.com, they may still have some beige ones in the warehouse, and they already offer special orders for other stuff, so at a minimum they won’t think you’re crazy for asking.

Mouse is a little harder, as the technology is legitimately much better now. Still, both Microsoft and Logitech sold a few native PS/2 mice with three buttons and a scroll wheel; I guess it’s possible that some of the ones that come with their own USB to PS2 converters would work fine even when re-converted back, but I’m not sure. If you get a ball mouse, remember to clean the crud-rings out from time to time.

I'll recommend some modern keyboards that are suitable for your retrokit - I'm a big fan of Unicomp keyboards myself, though they do not do N-key rollover, if that is something important to you. Their lighter shade (they call it 'white') is more of a grey than a beige.

You may also consider USB keyboards that can handle P/S2 protocol with use of an adapter (not all of them can do this very well). I have a WASD keyboard for my modern PC that I sometimes also use with my older machines. I would recommend them, but they appear to be out of business.