Windows XP, Windows 98, Workgroup and Outlook 2000

We have 4 computers set up in a peer-to-peer configuration. All of our
computers are running Windows 98 and Outlook 2000 (corporate / workgroup
mode on all computers). We have a windows workgroup postoffice installed on
my Admin. Assistant's computer so we can do our own internal email and
invite each other to meetings (using the Outlook calendar functions).

We want to upgrade our Admin. Assistant's computer to Windows XP. Will we
lose any functionality in our Outlook calendaring capabilities by making
this upgrade to XP? We are NOT upgrading our office products, just the
operating system on the Admin. Assistants computer.

Thank You!

Greg