I have that Verizon service you mentioned so I can access Internet when I travel. Do I need separate service at home, since the access time is slow and cuts off a lot? I had hoped $60/monthly would be all my service, but I guess I'm wrong. I currently have Comcast at home - can't get rid of yet. Do I need to sign up for another ISP? I don't want to hijack neighbors' wireless service. (anonymous)
Basically, your Verizon broadband card ($60/month) is not "unlimited" bandwidth - you have a 5gb/month limit. If you're only going to use your laptop (no other computers at home), and you aren't going to go over the 5gb/month limit, you could get away with only using that broadband card. However, it's probably going to be a good bit slower than a traditional Comcast residential cable modem connection. My Verizon card gets me about 1.5 mb/sec, where my Comcast cable modem gets 12mb/sec. (If you're getting less than 5mb/second out of your Comcast cable line, I'd be on the phone with tech support, raising hell - speed test here). And the Comcast account won't have the 5gb limit.
Also, the Verizon wireless broadband user agreement forbids you from using the card for gaming or streaming video (actually, recent court cases have overturned this restriction, but I'm not sure if it's a battle worth pursuing)...
If I were you, I'd pay for both services (Comcast cable modem and Verizon's broadband card) so that you're not counting and measuring your usage all the time. And if you want to use both your tower and your laptop at home, you'll should pick up a Netgear or Linksys Router (4 ports) with Wireless-G (54mbps) or Wireless-N (108mbps) so that you can use the l aptop anywhere within range of your router.