Correction from my earlier post - apparently the biometric passport requirement is only for passports ISSUED after Oct 26 2004.
http://www.flyertalk.com/forum/Forum...ML/007827.html
So:-
- passport issued before Oct26/04 and VWP country - no visa required
- passport issued after Oct26/04 and VWP country - either biometirc or visa required
Which in a way doesn't make sense in terms of security - most passports are valid for 10 years - therefore it will take 10 years for all non-biometric passports from VWP to disappear - so there will still be a large number of visitors undergoing different treatment and under different rules.