I don't thing you need to switch.
Just optimize you Win2k to boot faster.
I wouldn't recommand tiny XP and other "tiny" version of OS. Take the full OS and optimize it.
Tiny version are only interresting if you have a problem of Hard Disk space. If it is just for speed , memory or memory issue it is better to do the thing by hand.
Honnestly , keep you Win2k if all is working as you want. If the reason is just boot speed you can manage to make you OS boot faster.
If you want change the FE , I think the major one works on 2k too. Mala or AtomicFE for sure. GameEX should too , i think. And Surely MameWah too.