$100-$200 per user is super expensive compared to $0 per user. Have 200 employees, just for the exchange licesnse we are talking over $20,000 a year. Not to mention the proprietary x.500 Active Directory, Outlook seats, Windows licenses, Anti-Virus, Intrustion Detection, Spyware detection, etc... Not to mention the other long term costs of being locked into a proprietary Microsoft environment. Vendor lock-in will cost you dearly in the end.
So, yes that is "super expensive".
I agree, XP is the wrong way to go. Get rid of the super expensive Windows environment and move to GNU/Linux. Free yourself from the Microsoft lock-in and save a boatload of money.
Today is a good day for information-gathering. Read someone else's mail file.