I beg to differ Holger, I have bought these on ebay cheap, and they work just fine on boards that support them.
http://cgi.ebay.com/New-370-CPU-Celeron-3-Converter-Socket-for-Tualatin_W0QQ...
Here is one for 15$
THOSE adapters only reroute some signals. they leave the vcore generation completely untouched and you can easily burn your board's regulators. that's why they are so cheap. additionally those adapters don't change voltage levels of some important signals esp. PWRGOOD. this signal needs a level of 2.0V according to intel's specs. on some boards it is just connected to vcore. with vcore way below 2.0V the cpu will never start, not even with this adapter. everyone with medicore soldering skills could rework a S370 to achieve the same within 5 minutes.
but apart from all this: the bios (not even linuxbios) can distinguish between a fcpga/fcpga-ii board and a ppga only board. only if all boards were handtested by someone. this leads me back to my first thought: all slot1 and s370 boards get support for all slot1 and s370 cpus. the bios picks the correct handling routine during runtime like current bioses do,too. Holger