Here are my thoughts, as someone in Information Assurance you will be focusing on protecting the data within your network. The best way to do that will be to know a bit about all aspects of the network. This really only comes with experience. I personally have worked roughly 10+ years doing everthing from managing a large public school network, learning alot as I went but ultiamately worked with everything from configuring switches, firewalls, server builds, desktop deployment, AV deployment/management and enterprise applications like Exchange, including migrations. So I worked the trenches.
Later I took a postion as a consultant for about 5 years. Same sort of tasks involved but I then moved into working more with Macs, getting a bit more involved with cross-training on platforms and eventually took an interest in concentrating on security. I began doing more detailed vulnerability assessments which are fun to do. Run your automated scans, check to see if they are false positives and determine remediation steps if they are not. Sadly I had to leave the job due to some conflicts with management but it was time to leave anyway.
Since then I took a few jobs and I am now in my 2nd position as a Security consultant. So gain as much knowledge as you can. The more you know about the networks you need to protect, the better!