Information Security

A few months ago I joined a medium sized company as a systems admin.
The company's prior IT team did little in the forms of maintenance and
nothing in the form of security. I come from an administration
background but only common sense when it comes to decent security.
There are shared domain admin passwords, shared user logons and many
users have local admin on their pcs. I know best practice is to
separate the admins from the security team but this company views IT
as a necessary evil, ie theres 4 IT techs for 7 sites and around 500
pc users spread across the sites, all techs being at corporate. These
issues are being addressed but what I would like to know from the
community is the following:

Id like to assemble a toolkit both for gaining security control and
then maintaining it. Also pointers as to best practices and the like
would be most appreciated.

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