The comcast tools are only adequate if you want a basic page. The majority of the users commenting here find them slow and clunky to use. You do get a blog, guestbook, counter, etc but you are limited in design choices and will need a lot of patience.
If you want more control over what you put online, I would go with the 3rd party tools. Kompzer is a good free third party web authoring program. I use the Composer part of the SeaMonkey web suite from Mozilla. Kompzer shares the same software core. Kompzer has a built in upload utility but an ftp client would be better for uploading multiple files. My site is built with composer.
You will need an ftp client to upload to comcast. Comcast's file manager is slow and has limitations. CoreFTP Lite is a good free FTP client. One is built into windows also if you are on a windows XP, Vista, or 7 machine.
Comcast does not allow any server side scripting so if you chose a program that uses php or mysql for some features it will not work with comcast.
Thanks for recommending Kompozer. I`ve been to the Kompozer forum to read the tutorial /users guide , and it looks like it is more geared to the very experienced.. Very hard (for me)to understand just how to get started using it. Is there any others that may be geared more to the beginner? This one looks like it would take me quite a long time to understand at all.
Any of the the WYSIWYG html editors are going to have about the same learning curve. If you can use MSWord or other word processor you should be able to use a WYSIWYG html editor like Kompozer with little problem.
You can look for an editor that includes web templates, then you could just add your content. That would make it easier. You can look at the chart in the previous post to see which ones have templates included. Maybe another forum user can recommend a program that includes templates that would be easy to use.
Kompozer does not have templates but you can download free templates and use them with Kompozer. Google free web page templates and you should find a wide variety. Since you are starting out you should avoid CSS templates. It is a more advanced form of web page authoring.
If you have a Mac, iWeb works reasonably although it seems to be redundant in how it generates the supporting files.
I have an example page with links to pages I've built using various tools (Comcast PWP tool, Microsoft Word, Kompozer, iWeb, and by hand). I don't know if it would be helpful for you. But that page is built with Microsoft Word.