Any side-effects to ignoring the Windows Genuine Advantage Install popup

For someone looking after a small 50 Windows PC network (Mainly XP - some Vista), (all genuine copies), what would be the effect of ignoring the constant "Windows Genuine Advantage Install" pop-up prompts?.

Often when someone runs "Windows Update", they get this popup which results in confusion etc. etc.

What would be the effect if we simply ignored the popup?

If you have 50 PCs then automatic updates are best managed using something like Windows Server Update Services (WSUS) or Shavlik. WSUS is a free download from Microsoft and runs on your server, it acts as an update proxy (which will save you a lot of bandwidth), a management console that allows you to control which updates are deployed and a reporting engine that helps you determine which PCs are non-compliant.

I have never experienced an auto-update that required the user to go throught the WGA process. Add-on tools (like Windows Defender for XP) - yes, updates, no. Even if that is the case, WSUS enables you to pre-accept any EULAs on behalf of your users, so there should never be any interaction required by the users to install updates.

The effect of not going through the WGA process is that you don't get to install the product it is protecting.

I don't know how the PCs are managed where you work, but most groups of computers I've dealt with are running the Deep Freeze utility. When critical Windows security updates are released, I unfreeze the machines and selectively install the updates that should be installed, then disable windows updates and refreeze the computers. No nags for the users this way. If you are managing these across a domain (I hope) you could also try the same practices regarding windows updates, software such as SMS can automate updates for you and AFAIK has functionality to avoid certain ones.

There is more discussion on the matter here.