Write umlaut on Computer 1

Windows keyboard:

On the Windows US keyboard hold down the <Alt> key and at the same time on the number pad type the following:

For lowercase "ü" hold down <Alt> and type 129 on the number pad.
If 129 does not work, try <Alt> and 0252 on the number pad instead.

For uppercase "Ü" hold down <Alt> and type 154 on the number pad.
If 154 does not work, try <Alt> and 0220 on the number pad instead.

Also you can hunt down this and other special characters in Windows by going to Start > All Programs > Accessories > System Tools > Character Map.