EU privacy laws prevent the UK authorities from opening up UK criminal records to overseas governments. However a great deal of information is probably now passed on under the guise of 'anti-terrorism' (which overrides the privacy rules). Because of the secrecy which surrounds such issues, nobody really knows exactly what the US immigration authorities knows about UK citizens. So, while you might well get into the USA using the ESTA system, nobody is in a position to guarantee it.
For a more detailed answer, please see my first (two-part) post on this thread:
http://www.theanswerbank.co.uk/Travel/Question 709743.html
(See Dzug's post on that thread as well).
Chris