You can't "upgrade" between the two. You must uninstall Antivirus Plus via Control Panel, then run the MCPR cleanup tool (which is only good for removing traces of consumer products by the way, not VSE or other Enterprise products), reboot and then attempt your installation.
What version of VSE are you trying to install? Also is Windows 7 fully updated, SP1, IE10 etc.?
Many thanks for the quick response. I am trying to install VSE 8.8 and my machine is running Windows 7 with SP1 installed and I believe all programs are fully updated including IE 10.
Here's one concern I have about uninstalling Anti Virus Plus -- if I cannot get VSE to install, then I fear I will have an unprotected machine. Am I overly concerned on this?
You will have to uninstall AV+ first. Windows Firewall will protect you in the meanwhile. There's an installation guide for VSE 8.8 here: https://kc.mcafee.com/resources/sites/MCAFEE/content/live/PRODUCT_DOCUMENTATION/ 22000/PD22944/en_US/vse_880_installation_guide_en-us.pdf
You can always reinstall AV+ afterwards if VSE fails. Note that VSE does not contain a firewall whereas AV+ does.
If you have a license for VSE you must have a grant number, or the person who provided it must have one, that gives you access to the Enterprise Portal where you can get help with this.
I'm reading a lot here and I think that error 1303 is possibly because you may need to right-click the setupvse file and select "Run as Administrator" regardless of whether or not you are logged in as an Adminstrator. The machine's Admin account has even higher authority.
I could be wrong here so I'm hoping someone else will contribute to this.
VSE 8.8 Patch 2 requires the following hotfixes to be installed in the following order: Hotfix 805660, 778101, 820636, then Hotfix 846582.
2 of these HF are security related, and it's so complicated to install them correctly...