Securing workstations from IT guys

It's a catch 22 situation and I need to make our Windows Xp workstations 
appropriately secure. Secure from rogue Helpdesk personnel as well as 
network admins.
The HR guys are complaining that their 'offer' letters to prospective 
employees and some of the CVs that they recieve are finding their way into 
unwanted hands. I suspect both HR application vulnerability, for which I am 
undertaking some vulnerability analysis but I also need to protect the PCs 
that belong to Dept. of HR employees from rogue IT guys.

Here are the basics of what I intend to do:
1. Advise all HR users to shutdown their PC before they leave for the day.
2. Change all Local Admin passwords so that even IT helpdesk/other doesn't 
know them.
3. Advise HR guys to assign passwords to their excel/word files.
3. Do not create shares off c drive giving 'everyone' access.

But...because they are all connected to Windows 2003 domain, I still risk 
someone from domain admin group to be able to start C$/D$ share and browse 
into their c: drive, what should I do?

Also, it's easy to crack open xls/doc passwords, what else can be done?

Alternatively, Is there an auditing on PC that can be enabled to track/log 
incoming connections to C$ and pop up and alert whenever someone tries it 
out from a remote machine.

Pls advise!!