AVG Free is a great free antivirus and anti-malware program. Unfortunately, it does conflict with other antivirus programs. If you choose another antivirus program, then you will probably want to use the AVG removal tool to completely remove AVG from your system and ensure that no conflicts occur.
As much as I like AVG Free, I understand that other antivirus solutions can be better for different machines. AVG uses up a lot of system resources (which explains computer slowdowns after installing AVG). If you decide to uninstall AVG Free, then you will probably want to look into the AVG removal tool.
Now it's possible to use the add/remove tool in the Control Panel to uninstall AVG. Keep in mind, If you just use the add/remove tool, it will remove most of AVG from your computer, however, it is possible that Windows may not be able to completely remove it. This could lead to potential conflicts down the road. In particular, you might not even be able to install some malware protection if it detects traces of AVG in the registry. If it finds these traces, the installer may believe that you have conflicting software installed, which means that you might not be able to install a new protection program properly. It is also possible that remnants of AVG might trigger false positive alerts from your new program. In general, antivirus software packages don't play nice with one another.
Note that these conflicts should be quite rare. You're probably fairly safe just using the Add/Remove option in the Control Panel. It is still nice to be sure that you won't have any annoying glitches down the road, however. Therefore, if you're moving away from AVG for another antivirus suite, you will probably want to at least look into using the AVG removal tool.
About the AVG Removal Tool
The AVG removal tool is a fairly simple tool that was released by AVG to allow for a complete uninstall of their product. You can find the latest download for the AVG removal tool here. Note that this is a fairly intensive piece of software. It won't just erase the program, but it will take away any conceivable trace of AVG from your computer. It will clear out any user settings that may have been recorded on your computer. It will remove the relevant entries from the registry. It will even wipe out the records from the virus vault and clean up the folders. This program is only suitable for people who are ready for a complete wipe.
Note that it will require you to restart your computer and AVG warns that it could take more than one reboot, but that seems unlikely. Make sure that everything is saved and you're ready for a restart before you begin the removal.
When you're ready to run the AVG removal tool, just download it from the above link and click on the .exe file. It will run automatically. You will naturally need to confirm that you are really ready and wish to continue. Confirm that you're ready and then just let it run for a bit. Once the AVG removal tool has cleaned up your computer and restarted the computer at least once, you should be all set.
All traces of AVG should be gone from your system and you will be ready to switch over to a new antivirus package without any potential conflicts.
Screenshot by Author of AVG Removal Tool Warning (http://www.avg.com/us-en/download-tools)