I had a similar problem in getting MIDI jukeboxes to select my synth
rather than the Windows MIDI player, which is poor as usual.  I use a
small program called "Vista MIDI Picker" that allows you to switch the
MIDI output to any available device.  You can also modify the Windows
registry if you're more adventuresome.

This program gives you a little menu of the available options.  In my
case that is the Windows MIDI player or any of the three outputs of the
Edirol MIDI interface.  This download seems to work, though you need
a BitTorrent client to access it.

http://www.softpedia.com/get/Multimedia/Audio/Other-AUDIO-Tools/Vista-MIDI-Picker.shtml 
http://www.softpedia.com/progDownload/Vista-MIDI-Picker-Download-100053.html 

By the way, I'm using Windows Vista Ultimate which has many capabilities
that Vista Basic doesn't have, so I can't swear that this will work with
Vista Basic.

Seasons greetings
Jim Cook