Hello Doc-Z.
Basically Yes.
It runs on XP, which has been modified by Wersi to give optimum performance with OAS and Music Software. (So you can forget about playing Half Life or Tomb Raider)
Apart from the boot up screen, XP disappears, and so the Ikarus looks and operates like any other keyboard.
Like most manufactures Wersi have there own style format, however one of the options is a fully integrated version of Style works 2000, which runs direct from the OAS system, (No need to use Windows) so all conversions are done onboard the instrument.
The instruments can also import a style from Midi, so if a Yamaha style can be saved in Midi format, it can be loaded in to the instrument. (A Midi editor is integrated into OAS so that you can match up the style layout)
Hope this helps.

Bill