The free email clients that I know are Mozilla Thunderbird and MS Windows Live Mail (WLM). Mozilla Thunderbird Windows Essentials: Other Programs
I prefer Outlook because it has the most features and I've been using a long time so I know it better.
I have been using WLM a lot lately on my TEST box and it works fine for my needs.
Gmail (Google Mail) is free and offers IMAP, POP3, and web access.
I don't see a big problem with spam with Gmail or Hotmail.
Maybe their spam filters have gotten better, or maybe my habits have improved...dunno
You also said you had a malware problem - maybe your email address was compromised causing a lot of spam...again dunno.
Anyway, all of these are free options, so the only cost for you is the time and effort testing them.
I do have Outlook 2010 setup with Gmail, Hotmail, AOL, and at&t accounts and they work.
You could sign up for a free Gmail account and set it up in Outlook.
See if you can forward the Comcast email to that account.
Test drive it and see how you like it.
Just don't distribute your new email address until you're sure you want to keep it.