Sun Microsystems is buying German desktop virtualisation specialist Innotek in a bid to boost the appeal of its forthcoming xVM server platform for developers.

Innotek's open source VirtualBox application enables users to run multiple operating systems on top of whatever is installed on their desktop PC - whether Windows, Mac, Linux or Solaris.

The software can be downloaded for free, a key element in attracting software developers to building applications for the platform. Sun is expected to combine VirtualBox into a complete desktop/server virtualisation package for businesses, helping it compete with competing platforms from VMWare, Microsoft, Novell, Red Hat and others.

The deal is for an undisclosed fee.