Computer specification:
viewtopic.php?f=22&t=4922
OS: Anything you like. XP, Vista, Win7, Win8, I haven't tested Win10 yet but heard from others that it works as well. Or indeed Linux- the Juli@ card works fine in Ubuntu. Or even Mac (but I don't see any reason to choose for that).
Configure: Depends on what you need. You might not even need DirectWire...
License: Depends on the type of music that you play and on whether you're going to generate stereo/RDS with Stereo Tool (I would advise you to do that, it can give you a much better audio quality). In that case, you should get the FM Professional license which contains the Composite Clipper. If you play new music that's often not very dynamic and clipped, get the declipper. So then you would get FM Professional + Declipper (349 euro).