need Antivirus,firwall info - Norton AV "incompatible" with ZoneAlarm firewall

[Dmenace]

New pc with Win Vista op system.  Recently bought 12 month Norton AntiVirus 2010 & renewed 12 month ZoneAlarm firewall & was happy with both on old Win XP pc.
Shortly after reinstalling both on new pc, ms Outlook was unable most days to receive new mail and secure banking web sites were often inaccessible.   Removed both for a bit - no problems.
Finally reinstalled Vista op system then ZA firewall.  Reinstalling NAV, it tells me NAV2010 is 'incompatible' with ZoneAlarm.
I've likely raised my risks with several software makers doing separate jobs.
Despite having paid subscriptions, I may need to stay with 1 co. for both tasks (ZoneAlarm Extreme Security or Norton Internet Security).
Does anyone have experience with these 2 companies? Success with NAV + another firewall maker besides Windows firewall?  Experience with Norton or ZoneAlarm full task products? I've heard complements + horror stories on both.  Many thanks.

[soybean]

Is this a home PC, or is an office/business PC?

[Dmenace]

Is this a home PC, or is an office/business PC?

This is a home pc.   Very frustrating as I couldn't log into bank accts. to check acct, pay bills ("Internet Exp can not display this page").  I was unable most days to receive new mail via ms Outlook: error codes 0x800CCC92, 0x800CCC90, 0x8004210E; I was still able to read new mail via ISP's web page mail.   (ISP recently changed email service from their server to Win Live; had 'Outlook unable to Rev new email' once since then).
   Outlook seems to be working now.   I realize not smart to work with no AV; visiting only "safe" sites  for now.    Had no trouble with [ZA firewall + Norton AV] before (Win XP, old pc) but may not work together on new Win Vista pc.   I may also try ZoneAlarm tech help again.   Intend to upgrade to Win7 when I get rid of current problems.  Thanks for your help.

[Dmenace]

ps. interesting that, on days Outlook unable to Rcv email, I was usually able to receive new mail by turning off Norton AV 'scan incoming email' until new email downloaded from ISP server then turned back on.   Also, Norton, ZoneAlarm Help checked, both pgm's "working well".  Thanks again.