There are various ways you can control patch installations for some of your Microsoft systems. However, Microsoft retired extended support for Windows NT Servers and Workstations in 2004, so you'll need to look into retiring or upgrading your NT systems. Microsoft's Windows Server Update Services will enable you to manage the distribution and schedule the installation of updates that are released through Microsoft Update to computers...
on your network. This is easier to use than the command-line tools QChain.exe and Qfecheck.exe, whose chain updates together so that multiple updates can be installed, and verify that your computers actually have all the fixes you wanted to install.
Unfortunately, Cisco does not have anything comparable to Microsoft's patch management tools, so your routers and firewalls are going to require a manual installation. Even if you use a patch management tool on your Windows systems, you will still need to manually test any new patches before rolling them out across several machines. Testing before deployment is a major roadblock to full automation, and an automated patch deployment should only be considered for systems where information confidentiality is more important than availability, or where the risk of an attack is deemed to outweigh the risk of downtime. Another related problem with patch management tools is that they are inclined to approach patches as just another file distribution task. Because this is so, they tend to lack patch analysis capabilities and an understanding of patch interrelationships.
There are several patch management tools for Windows, including products from Configuresoft, PatchLink, St. Bernard Software, Ecora, BigFix and Shavlik Technologies. Shavlick developed the HFNetChk™ scanning engine that's used by Microsoft's Baseline Security Analyzer. There is a Basic Edition of their HFNetChkPro that is aimed at smaller organizations that do not need advanced patch management functions, such as scheduled scans and e-mail support. More information can be found at their site http://www.shavlik.com/hfnetchk-windows.aspx.