fair play to parkers, but my own personal experience of agencies is not a very positive one. After registering with a stack of agencies, doing all of the relevant computer tests etc for each one, i had to chase and chase for feedback on applications and interviews. in the end i gave up on them and applied for jobs directly in the newspapers. had a fantastic response and got offered several jobs which i could then take the pick of.
try going it alone as well, and don't rely only on the agencies.