For internet access within the home, you only need a wireless router which connects directly to the cable modem, then the router connects to the wireless capability in your laptop. The PC can connect directly to the ethernet port of the router as well. Both machine will have access at the same time. That's assuming you have a wireless adapter in your laptop. If not, then use its ethernet port to connect to the router as well.
For internet access out in the "real" world, you can use wireless hotspots such as internet cafe's, hotels, etc.for connecting directly to your laptop's wireless adapter..
For such access out on the road without such a hotspot, yes, an aircard through your phone company is your best bet, but be aware they are fairly expensive.
Hope this helps.
I have an Acer netbook with WiFi capability. I receive internet for my home PC from Comcast through an ethernet cable. I want to get portable internet access to my laptop. Will I need an aircard contract through my phone company. Is that the only option? Could this replace my cable for my home PC? Basically, what is the best, consolidated method for internet for a PC and netbook? Will I need 2 different things (one for each piece)? Would an ethernet hub split my signal and allow me to "plug in" my netbook while at home?