Windows XP SP3 is now back online for automatic download via Microsoft’s Windows Update service. This comes shortly after the hasty withdrawal last week of both Windows XP SP3 and Vista SP1 following the discovery of a compatibility issue.

The compatibility issue involved Microsoft’s Dynamics Retail Management System, or RMS and affects both XP SP3 and Vista SP1 . Microsoft RMS is a POS (point-of-sales) and store management software designed for SMEs.

Excerpt from Network World:

Tuesday, the company said it had added a filter to the download sites to block the service packs from RMS users only. A permanent fix is in beta and should be available in May, the company said in a statement to media outlets.

Windows XP SP3 will be the final service pack for the venerable Windows XP operating system. Anecdotal evidence from a number of TR members indicate that they will continue to install Windows XP on new Windows Vista-only machines beyond the June 30 cutoff date.

It is just as well that extended support, which gives free security updates, will continue until April 2014.