The words used for naming a computer mouse are different in Brazilian Portuguese ("mouse" just as in English) and in European Portuguese ("rato", an expected translation): http://pt.wikipedia.org/wiki/Rato_(informática)
In fact, most (not all) of the vocabulary for informatics in Brazilian Portuguese is just adopted from English (mouse, site, online, etc.). In Portugal, most of it is replaced by Portuguese words (rato, sítio, em linha, etc.). I would not know, however, what characterizes this vocabulary in the other Portuguese speaking countries.
A tip: look for the English word at the Wikipedia in English, and then click on the "Portuguese" link in the "Languages" column at left. That way you will find the word for it in Portuguese, usually mentioning the distinction between Brazilian and European versions.