IMAP in a business environment

I have a user who needs to access her e-mail on two different computers. We do not host our own e-mail — it is currently hosted on a 3rd part ISP. I am considering setting her up to use IMAP.

Has anyone who has done this in a small business enviroment have any feedback? Possitive or negative.

One note: she gets a lot of attachments, anywhere between several KB to 8 MB.

Thank you for any information.