AFAIK, you can't do that unless the program you're using has the option to set the output (such as skype, for example).
Makes me wonder if there's any software that allows you to redirect sound to a different output... hmmm...
EDIT: So, i've found this: http://www.indievolume.com/ It says for XP on the homepage, but the download link says it supports vista and 7 (32 bit only).
Seems like it'll allow you to choose what output your applications are using on per application basis. Seems pretty cool, but, it's not free... Lets you try it for 14 days before you need to pay to use it more. Might be worth checking it out. Let me know how it goes if you do decide to use it!
Makes me wonder if there's any software that allows you to redirect sound to a different output... hmmm...
EDIT: So, i've found this: http://www.indievolume.com/ It says for XP on the homepage, but the download link says it supports vista and 7 (32 bit only).
Seems like it'll allow you to choose what output your applications are using on per application basis. Seems pretty cool, but, it's not free... Lets you try it for 14 days before you need to pay to use it more. Might be worth checking it out. Let me know how it goes if you do decide to use it!