If you are worried about your company reading your instant messages, you can use https://meebo.com to send them encrypted.

Notice the ’s’ at the end of https. This will create a secure, encrypted session between your PC and the the Meebo servers. While your employer (or school, or network) can normally view any IM’s you send, encrypting this traffic will prevent them from seeing them.

Note that while this protects your from your employer and local network, this doesn’t protect you from anyone at Meebo, or at the other end of your chat.