Learning Perl and/or Python is important for your long term skill set. If you've got security responsibilities right now, I'd skip the programming until you're up to speed in some other areas.
First, learn TCP/IP if you haven't already. I recommend W. Richard Stevens TCP/IP Illustrated volume I. Some of the stuff on Ethernet is dated, but the book is wonderful.
After that, explore the areas of network security that are most applicable to your responsibilities. I'll suggest several books to start, but supplement your book reading with experimentation and online research. A topic that is interesting to you may only get a half a page of coverage in a book, but there are probably more in depth articles available--use Google.
For IDS, install Snort on a test machine. Read Network Intrusion Detection by Stephen Northcutt. The book is several years old so you'll want to supplement it with the Snort documentation.
For penetration testing and applied security concepts, read Hacking Exposed and play with some of the tools in a test environment (don't scan/probe/attack any system without permission.) Other posters may recommend Counter Hack Reloaded instead; I've heard good things about it, but I haven't read it yet. Either book should be fine. Also, install Nmap and read the Nmap documentation. Make sure you understand the different scanning modes and OS detection.
For perimeter security, read Inside Network Perimeter Security by Stephen Northcutt. Try to get your hands on a router that you can practice configuring (if you don't have significant experience already).
For Windows-specific information, reading Hacking Exposed Windows. Also, Google and read "A L0phtCrack Technical Rant". Make sure you understand the difference between LM and NTLM and how to turn off LM hashes--Google is your friend. Experiment with the tools in a test environment.
For Unix-specific information, I'm hard-pressed to make a recommendation. I enjoyed Practical Unix and Internet Security by Gene Spafford, but my copy is from 1996. There is a 2003 edition, but I have not looked at it. There are other Linux-specific books available that may be more helpful to you.
I apologize that some of the books I recommend are a little old; my recent reading has tended to focus rather deeply on narrow areas rather than on general material.
Best of luck to you.
BS in IT: Security, CISSP, CEH, EnCE. MS in progress.