Source code isn't much use to the average user - even if it includes the code to the drivers for the stuff the hardware vendor just embedded. And that's even if it wasn't written in something you can't even compile on modern systems.
Of course we're about to be in the same position with the next-gen kit that only supports XP.
We'll end up with all the data from the XP and 9x machines written over a local network to a win7 box, which can also see the proper network and therefore be backed up properly. No more VNC/RDP into the XP machines though - unless we can find a workaround - and we probably can.
* zinio (buy magazines to read on a tiny screen - really?)
* 7 digital music store
* tunewiki/motorola music player - a new, slower UI with every update (seemingly every week)
You could easily count motoblur on that list as well, and with a non-rooted old android (like all the other waterproof phones), you can't disable them entirely, block them from updating or move much of their bloat onto SD card (obviously, because then I could delete that).
So for now, rooting is still needed. Unfortunately with up-to-date firmware, it's also rather tedious and risky on this handset.
With systems that are bought as a hardware-software package it's often the drivers that don't get updated for 10 years, instead they are replaced with the new model. The UI can often be made to run.
If there's no hardware involved, XP in a VM will be the way to go, but there's no hope of that for the really old stuff, and I'd be surprised if the system could communicate properly with the hardware even on the new stuff.
There's 1 major advantage compared to the end of Win98 - at least XP has good support for USB sticks so you can get your data off.
I miss Windows Explorer - I still haven't found a decent full-featured file manager for Linux, and I've tried most of them.
Opposite here - I miss a tabbed view when I use windows explorer (as a mainly GUI user on both) In answer to the original question (in the unlikely event that anyone cares). OpenSUSE (dual boot with win98) -> Ubuntu (dua boot with XP) -> XUbuntu (thanks to unity) + Ubuntu Natty (Classic Mode, netbook)