I'm not sure how you intend to use your speakers and mic and such, but I don't think a mic input is very common on speakers. Headphone outputs are much more common though.
Anyway, if you intend to just use one of those desktop mics, just buy an extension cable if it won't reach all the way to your soundcard.
If you're intending to use it with a headset to plug into both ports to game with or something, then take a look at this simple switch:
http://www.amazon.com/Plantron...r-Switch/dp/B000069E1V
I bought one from newegg a while back, although they don't seem to have it anymore. I got it because my speakers didn't have a headphone output jack, so I plugged this into my soundcard instead, and plugged both the speakers and headset into it. Painless switching between the two.