Sorry, per #3 [thanks vilbara, wish I'd actually read your comment first!], it looks like xubuntu and lubuntu were workarounds for the initial "PAE-free" release of 12.04, but have already inherited the PAE requirement from mainline Ubuntu for 12.10, so... the 'grace period' offered by those distributions has already expired.
[I'd be happy to live insecurely but cautiously without NX emulation - AFAIK it wasn't even introduced to Ubuntu until relatively recently, see bug #369978 - maintenance of the patch being claimed as one reason for going PAE-only - even if this required manual installation of a specific 'nopae-insecure' kernel with screaming warnings after the fact, but given the other limitations it seems unlikely that many of the 'hot new features' post-12.04LTS would be available on my hardware anyway.]
Sorry, per #3 [thanks vilbara, wish I'd actually read your comment first!], it looks like xubuntu and lubuntu were workarounds for the initial "PAE-free" release of 12.04, but have already inherited the PAE requirement from mainline Ubuntu for 12.10, so... the 'grace period' offered by those distributions has already expired.
[I'd be happy to live insecurely but cautiously without NX emulation - AFAIK it wasn't even introduced to Ubuntu until relatively recently, see bug #369978 - maintenance of the patch being claimed as one reason for going PAE-only - even if this required manual installation of a specific 'nopae-insecure' kernel with screaming warnings after the fact, but given the other limitations it seems unlikely that many of the 'hot new features' post-12.04LTS would be available on my hardware anyway.]