The version of Avast you are using, although still supported for now, has been superseded by version 5; currently at 5.0.545.
Do you wish to upgrade to this version (recommended, by me and probably most others) or stay with the one you have?
What version of XP do you use (SP2, SP3?)
In general terms, you would download an install and save it (and download and save any other files needed, too) prior to uninstalling.
Whenever you are uninstalling/installing an AV (or firewall) and your computer is unprotected, it is best to be disconnected from the web during that time.
Security software installs and uninstalls should be run from an account with admin privileges.
The current version of Avast 5 can be found here for downloading. (The Avast 4.8 versions can also be found lower down on that page.)
The Avast uninstall utility can be found here.
The procedure would be to:
right click the tray icon, select “program settings” then “troubleshooting” and disable the Avast self defense module. (Opinion varies as to whether that is necessary or not. It can do no harm, and sometimes prevents the uninstaller from not working correctly from what I’ve seen.)
Uninstall via control panel>add/remove programs. Reboot. (If there were problems with uninstalling, reboot into safe mode, see next.)
Run the Uninstall Utility you downloaded. If there were problems with the uninstall, this needs to be run in safe mode. Reboot (into normal mode)
Run the Setup file you dowloaded earlier, to install Avast. Reboot as prompted.
Reconnect to the internet, get updates (will probably happen by itself.)
Click on “start” (at the bottom left of the screen) then “turn off computer” , then “restart”.
It will shut down, but immediately go through the startup routine.
“Why is it still in version 4”
That I don’t know, maybe the version 4 updater in your installation was not set to update the program automatically.
If you click on the tray icon, select “updating” then “program update”, that may be a quicker and more straightforward way to do it.
Some users reported problems doing that in the early version 5 versions, though, which is why I suggested the alternative procedure.
You could try manually updating the program, but if you run into problems, go through the full procedure. Whatever you want to try.
OK. I followed the steps and everything went smooth. (Didn’t get a chance to use uninstall utility though)
Now this version 5 is not accepting my old licensekey when I click on ‘Insert licensekey’ button. Getting error ‘Invalid licensekey’. Still until august I am covered with updates.
Try writing to sales@avast.com with your subscription information, you could include the URL to this thread, and they should send you out a replacement key.
avast! 5 Pro license convert from 4.8 Pro license. Try http://www.avast.com/resend-license.php now, fill in the form giving your email and 4.8 Pro License key and they will send the new license file to you (presumably it will check you have a legit 4.8 Pro license first).