Tools a Windows administrator cannot live without
I just joined a small computer lab which basically uses all Windows boxes and a few Windows Sever 2003. Coming from a *nix background I am missing all the nice tools that we have for diagnosis and troubleshooting. My question is what are the safe, free (not terribly concerned if it is like beer or freedom -both acceptable) tools out there that Windows system admins use for their day to day troubleshooting (network, applications, servers etc).
I am aware of the tools that come with Windows (and their limited capabilites) - so my query is with what do you fill in your arsenal? (may be a list of win versions of tools that come in standard linux distros)