To be 100% honest, it would be very hard for me to not have my computer. Everything from grades, attendance, typed projects, to using my Smartboard has to be done on my computer. This is only my 8th year of teaching and my first year I still did grades in a traditional gradebook and I kept attendance in my gradebook for my first 4 years of teaching. But I type up all of my own projects, worksheets, and test. I use it for power point presentations and internet research.
Needless to say, for me, it is a vital tool. I know teachers didn't have them even 10 years ago, but I think it helps make me a better teacher.