Do I need to deploy antivirus and anti-spyware software to all the PCs on my network?

Solution 1:

Modern Anti-virus software should already provide anti-spyware countermeasures. Symantec AV Enterprise, which is what I use on Windows based PC, does.

Solution 2:

I think you get the biggest bang for the buck just by using the Microsoft provided anti-spyware solution, Windows Defender.

It has the following advantages:

  1. Updates pushed out via Windows Update
  2. Supports Group Policy
  3. Free
  4. Supports Windows XP and up including Server OSes

Alternativley you can look at Microsoft Forefront Client Security which provides an integrated anti-virus and anti-spyware solution.