While not much help, the fact that several AV programs are experiencing exactly the same problem suggests you have a configuration issue somewhere.
I can't really help you pinpoint where exactly, but if you need to enter in any special proxy settings to make a web browser work, then those same settings need to be applied to the AV program's update manager. You should also check the HOSTS file to make sure some malware didn't somehow slip through, inset a bunch of entries blocking the most common AV update servers.
I can say that your running Vista x64 has NOTHING to do with this. I'm running Avast on Vista x64 right now, and have been since I got this system, without any issues.
Finally, I will say that Internet Explorer is wildly unsafe for any kind of regular use, and Outlook isn't exactly a wise move either. You really should replace those with something else. IE can be replaced with Firefox, Seamonkey, Flock, Opera, or Safari. Outlook can be replaced with a few dozen different email programs, and if you need the calendaring function, there's always Mozilla Sunbird/Lightening, Google Calendar, and probably quite a few others.
I don't know if this is a OS problem or a software problem so I'm putting it in the Virus forum and the Vista forum.
This one that has me completely boondoggled.
On my recent trip back to the states I got my wife a nice new compact Dell XPS 1330 laptop.
I didn't know it at the time but it's a 64 bit version of Win Vista home premium SP1. (This may or may not be the key to my problems, the 64 bit part)
It came preloaded with Norton internet security for a month so I went ahead and turned the crap-ware on and figured I'd use it until I did all the updates the machine needed and then switch it over to Avast.
Internet works fine, windows update works fine. Norton and windows defender cannot find their respective up date servers.
Time passes and last night I removed Norton, updated windows defender (can update now) and then through on Avast.
After reboot I can not get IE to load a web page, but Outlook works (can send/receive) and Avast cannot update itself / cannot find server.
Strange.... I try turning off the "Web Shield" module of AVG and now IE can load pages but still Avast cannot connect to update it self.
I go to the avast help/support/FAQs and add every thing that I can as an exception to windows firewall but still can not connect to update server.
I then remove Avast and place AVG on the Machine.
Same problem: Can load web pages but cannot reach Anti-virus update server to update definitions/program.
I do the firewall safety dance again and still no dice.
I remove AVG and try Anti-Vir
Same problem again?????
I give up and go to bed
All Anti-virus's that I tried stated that they were Vista 64 bit compliment and I DL'ed them from their own home pages.
Anybody have any clue what's going on or how to correct it??? How do I get my Antivirus to update it self when the preloaded one couldn't do it??