> The company can do as they wish with their property but I'm interested in where one draws the line.
I'm not sure how universal that is. Personally I always prefer keeping my stuff away from a work machine, but this does not mean that surveillance is OK.
Where I live (Western Europe), it doesn't really matter whose property it is, surveillance is not allowed. If your employer is analyzing your web traffic and/or reading your e-mails this is illegal even if it's on their property or their network.