Aka Remote Administration Tools .
Answers:
i've never hear it referred to as RAT but if it is what I am thinking it is next it's simply referring to using tools that provide remote rule. An example might be RDC or remote desktop built right into window. Another one could be logmein.com I use both intuitively. One for business and one for personal at home use.
logmein.com is a great free tool to access workstation's for free.
no, im pretty sure RAT stands for Really Attractive Toes.
RAT = Remote Access Tool
Its does like peas in a pod entry (or similar to) Remote Desktop.
You REALLY dont stipulation a RAT as you own one already within XP call Remote Desktop