Remote Desktop and Security

I'm pretty much a newb at wireless. Now that I've moved into a place with only one cable jack, I've decided to go wireless. I want to be able to control my 3pcs and 2macs all with one tool if possible. Right now I'm doing Remote Desktop with the PCs and TightVNC with the Macs, but I'm thinking there's got to be a better way.

Also, the sticky at the top of this forum for wireless security - the links don't work. Can someone give me a good guide to setting up my wireless securely?

Also, I've just purchased a Linksys WRT54GL. Being fairly newb, are the standard security features good or should I flash it with some custom thing like some people recommend on the newegg reviews? Now that everyone in the house is going to be getting online wirelessly I need to make sure their credit card numbers and what not are safe.

Thanks