Uninstall Norton before Download Avast?

[MojaveRacer104]

Hi,
I'm new to Avast and Alwil.  I currently have Norton SystemWorks 2003 and am due to renew. Instead, I want to download Avast 4 home, and replace the Norton.
I understand the need to uninstall the Norton before installing Avast, but I am reluctant to uninstall the Norton before downloading Avast.  Last year, when I brought a new computer home and hooked up to DSL for the 1st time, before my firewall was finished downloading, I was deluged with spywares, trojans, etc. so that my computer became almost unworkable immediately.  Several days later I found SpyBotSD and it fixed most of my troubles, tho' some damage remains.
I want to avoid such trouble now, so I am reluctant to bare myself while preparing to switch over.

[Eddy]

This is easy to solve.
1) download Avast
2) disconnect from the net
3) remove Norton
http://service1.symantec.com/SUPPORT/nav.nsf/docid/2001092114452606
4) reboot
5) install avast
6) reconnect

[Spiritsongs]

   After I COMPLETELY uninstalled ( & other files, folders, &
     registry entries ) Norton Antivirus 2004 and finished
     downloading & installing Avast, I was surprised to find
     NO detection of anything after running a "through" scan.
     Since you now have a firewall & antispyware program(s)
     in place, there is less chance of getting a virus, etc .
     If you do, programs like Avast & Ewido can remove them .

[MojaveRacer104]

Great guys!  thanks!  These are the sort of answers I was seeking!