Are you using an @comcast.net email address for your work? What about @(city).rr.com? @verizon.net? @cablevision.net? Or some other email address tied to your ISP?
Have you thought about the long-term considerations of doing so? When you use an ISP email account, you are now bonded to that service provider. Now, if something else comes along that's newer/cheaper/faster comes along, what do you do? You have to either stay with your old provider in order to keep the email address, or forfeit it and potentially abandon a key way for people to reach you.
By using an ISP email account, you also run the risk the company can either go out of business or suffer a name change that will eventually make your email address seem antiquated. Think @earthlink.net, @mindspring.com, @prodigy.net, @compuserve.com, etc.
What can you do instead? A step up from an ISP email account would be one of the major free email providers such as Gmail, Hotmail, or Yahoo! Mail. These accounts aren't tied to a particular provider, so you remove that dependency. But, I'm still a bit leery of doing business with someone that's conducting all of their affairs through email@example.com or firstname.lastname@example.org. These accounts are easy to get... which is both good and bad.
I recommend that people register a domain name and use a service such as Google Apps in order to have a completely portable name. With about 15 minutes of knowledgeable help, you can have your own domain name registered AND a free email account with Google that includes that domain name. I registered bbhart.com years ago for myself for this purpose and haven't looked back since. Since then I've moved three times in two different states without ever losing touch with anyone.
If there's enough interest in this, I'd be happy to put together a post that outlines how to register a domain and hook it up to the FREE Google Apps!