Also in the UK the FSA requirements are, while pretty woolly and open to interpretation, based around industry de-facto standards such as ISO 27001, CobIT, ITIL etc, with the main aim being for an organisation to put in appropriate controls based on the data or processes.
The Data Protection Act is also high up the list of important regs to meet, especially now the ICO can levy fines for failure to protect personal data.
PCI is currently one of the top scoring regulations to comply with, as the drivers for financial services organisations are commercial. While passing PCI requirements is no guarantee of security, failing them presents very significant risks!