I took a cisco course last year and that enabled me to pass the CompTIA Network+, A+ and the Cisco CCNA certification tests.  Depending on your background in networking would tell what I would do in your position, if you have a good bit of experience, maybe look over some online resources or go buy some certification material at your local bookstore.  A+ should be a first priority because it deals with all the hardware and software of basic computers and is considered a necessity as far as i'm concerned.  As far as networking goes, Network+, Server+, any of the CompTIA certs would be good because they don't expire like Cisco ones do.  Now if you don't have much networking experience (setting up a network at your house with a switch and a netgear plug and play router dosen't count) then finding a course in networking at a local vocational school or college would be your best bet.  Let me know if you want any more info.