Apart from the VB vs C affairs that might appear, I think you should learn something that gives you freedom of choice, and doesn't bind you to a specific operating system (btw, vb is a bit expensive too). Try C or C++ with a free compiler. There are lots of good books on them, and you can find tons of resources on the web. Try www.programmersheaven.com or a webpage like this.
About the administration part, it will depend on the OS you want to deal with, but anyway, if it's linux, check the Linux administration guide.. www.tldp.org, somewhere there. And read documentation for your programs, always...
Do you want to know how to admin an Apache webserver, for instance? Ok, go to httpd.apache.org and fetch the documentation. I always think the manual is the first place to search in..