Advise

Hi all,
I am fairly new to NT administration. In the office we are running Office’97 and Outlook 98 (Corporate Mode). I was asked by my boss to go out and buy a copy of Office which version of Office should I get? What about Outlook? Most of the Workstations and servers are NT 4.0, we are planning to migrate to Windows 2000 which leads to another question when it’s time to migrate, which OS should I upgrade to? 2000 or XP. Thanks for your time!.