How Can Outlook Handle Two Separate Businesses' Email Addresses?

[smmforum]

I work all day for company "A" and have my laptop hooked into their server.
I receive that company "A" email into Outlook. I also have my own business
(company "B") that I work on part-time. I want to use the same Outlook
contact list and calendar in the same user profile (many of my company "A"
contacts and company "B" contacts are the same). How can I receive company
"B" email into Outlook without company "A" potentially seeing it? Can I set
up Outlook so that I only receive company "B" email on my laptop when I am
not in company "A"'s office? For instance, if I go out at lunchtime to
another location, or after hours at home, I receive/send my company "B" email
then. But when at company "A"'s office and hooked into their server & system,
I only receive company "A"'s email. How can I set this up? Thanks!