If I was to buy a 7.1 sound card, will I still be able to use 5.1 speakers and headphones with it? Silly question I know, but I need reassurance every time I go to buy something. 
Oh, one more thing, if I was to use 5.1 speakers during the day, and often switch to 5.1 headphones at night, how do I go about avoiding having to mess around with speaker jacks at the back of my PC every time I change them? I've seen something about an amp box provided with the Speedlink 5.1 headset, does that do this job?
Many thanks for any help.

Oh, one more thing, if I was to use 5.1 speakers during the day, and often switch to 5.1 headphones at night, how do I go about avoiding having to mess around with speaker jacks at the back of my PC every time I change them? I've seen something about an amp box provided with the Speedlink 5.1 headset, does that do this job?
Many thanks for any help.