... be sure to leave it truly disabled on your computer unless you are needing it.  It initiates processes that start when you turn on your computer that run continuously whether you are using Skype or not.

This presents two problems.  As it creates a peer-to-peer network (similar to what the original Napster did) that Skype can use to "hijack" some of your computer's internet bandwidth, even when you're not making calls.  It can also bog down your computer and make it run slower, although these days that is not such a big issue.

The second problem is that there are lots of computer-bad-boys-and-girls, especially in Europe, who are actively creating Trojan Horse programs and sending them to Skype users, and trying to find ways to hack into your computer using the Skype network.  I would hate to read here that you were the victim of an attack.

Best to totally disable Skype when not using it for those emergency calls!

I humbly offer my services in this area in case you think your computer has been compromised.  Spending time with you(r computer) would be lots of fun!  Even tough I'm based in Tucson making the trip would be worth it (I'm sure you could find someone local to help out, but hey, a gentleman is always gallant!)

There is a good Wiki article on Skype that gives more details for the techies among us.