Where I work the minimum certification we look for trainees to have is the CompTIA Security+. It's a very easy qualification to obtain... if you know what you're doing you can buy one of the guide books, revise for a while and then just take the exam... no need to go on a boot camp or anything like that, it's really not that difficult at all.
More senior members are expected to have / be working towards the CISSP.
If you're focusing on network security then you can't go wrong with Cisco certification. CCSP is the security-specific one. However, going vendor-specific does narrow your options a bit.
You may want to browse sites such as Job Serve to see what skills are currently in demand and what qualifications / certifications are sought after by employers. That will give you a good idea of what you should be aiming for. Bear in mind, however, that the goalposts can move, so it may take you a couple of years to get somewhere only to find that those skills/certs are no longer the must-have thing any more.
For some free stuff, pop along to
Infosec in London later this month, attend the seminars, speak to the vendors about what's hot at the moment and what's not. Just try to get a feel for the industry, to see if it's really something that you want to get involved in.
