Instructions, do this first:
Download the Norton Removal tool here: http://service1.symantec.com/Support/tsgeninfo.nsf/docid/2005033108162039 then save it to the desktop.
Download the AV (and firewall, if any,) you wish to install in its place. Save to a folder or your desktop.
I use Avast AV, I read that Avira is very well liked among its users, and easy on the RAM. (Have been a bit tempted myself, but Avast has never given me a reason to want to change.)
With the current amount of memory you have, and the likelihood that the cpu is similarly spec'd, you may run into difficulties if you want to also run a resident AS, like SpywareTerminator, so I'd recommend demand scanners such as Superantispyware and/or MBAM, that only use resource when they're open. SpywareBlaster, by Javacool, is a useful blocker/immuniser that uses no resources, except when updating. Do that weekly. There are also firewalls that are two-way (the XP one is inbound only), Google (or see the sticky) for the ones that are low-resource.
Disconnect from the web. Go to "control panel> add remove programs", locate the entry for Norton, select "uninstall". Reboot as/when prompted. It's possible the browser may open to connect to Symantec. Just close it if it does. Locate any other Norton or Symantec products in "add/remove programs", if there are any left (assuming you don't want them) uninstall.
Run the Norton removal tool downloaded earlier. Reboot.
Wouldn't hurt to do a disk cleanup at this point (or before you start all this) "Start>All Programs>accessories>system tools>disk cleanup."
Don't select "compress old files", unless you're short of disk space.
Install your new AV. It may ask for a reboot during the setup sequence. Make sure a firewall is turned on. "Start>control panel>windows firewall" if you don't have a third party one, yet. If you have downloaded a third party firewall and prefer to use it, install it.
Now, if the computer is running OK (and it should be) reconnect to the web, and update your AV. Good idea to run a scan at this point, or soon.
Disconnecting from the web is only necessary when changing AV or firewall, because of the pretty much total lack of protection while either is disabled/removed.It can be done by removing the network cable. The same procedure is not necessary for downloading and installing an antispyware.
Bought a second hand system running Windows XP with preloaded Norton. It uses a load of memory and subscription has expired. I hear there are good free packages available eg Avira, Comodo, Spyware Terminator etc and I would like to load them. Trouble is, how do I first delete Norton?
ps, system has only 256 meg DDR ram which I intend to increase to 1G.
pps, I'm new to the update game.