1. The way I prefer is to use the Windows language bar to switch the keyboard layout to German QWERTZ layout. The physical keys are still labelled for English use but it’s not difficult. Z and Y are swapped but the other 24 letters of the English alphabet stay in place for German.
For a larger picture and licensing details see http://en.wikipedia.org/wiki/File:KB_Germany.svg
Microsoft also offer Visual Keyboard to make it easier to work with different keyboard layouts. http://office.microsoft.com/en-us/visio/HP010501061033.aspx
2. Another method is to use the Windows Character Map