I think the IT Manager has one of the most challenging jobs in the IT world. He or she has to know how the technology works at the nuts and bolts level and at the same time understand its implications from a business viewpoint. They have to make quality recommendations about purchasing decisions and the adoption of specific technologies. They are generally responsible for managing people, knowledge transfer, IT functionality, and doing it all within a traditionally tight budget and within 60-80 hours a week.
I have felt your pain.
TechNet has recently built a resource site specifically for IT managers. It is hosted by a co-worker and friend Kevin Remde. The thing I love about the site is that it integrates a wide range of valuable content that spans the range from Licensing to Learning to Business productivity and beyond. The site is a free resource and is there to make life easier for you if your an IT manager.
If your an aspiring IT manager take a look at the site and get familiar with the kinds of issues and solutions that you are going to face. This is one of the best IT Manager resources I have seen to date!