I would say split up your list and look at each component separately on the web for appropriate replacements. But here's my recommendation (you're bound to get others):
Printing - CUPS (the package name in Ubuntu will be cupsys, I believe)
Email - Novell Evolution (should also be in the Ubuntu repositories), I think this should let you login to the exchange server and even use the calendar functions
Network Drives (I assume you mean drives, not drivers) - Samba for Windows shares, NFS for unix style shares
IM - Gaim (good for msn, yahoo, aim, icq, etc) or specific linux client like aMSN for an MSN network
Like I said, I would look at each thing you want to do and then look on google or here
for a linux program that's equivalent.