This could be due to some remnants and left overs or those antivirus softwares detected by McAfee installer. Please try these sequential steps and keep us posted on the outcome ;
Run the concerned removal tool for those third party security software from our database we have composed for our customers : http://service.mcafee.com/faqdocument.aspx?id=TS101083
You need to run all the three : Norton/PC Cillin & radial Point.
The run McAfee removal tool from here and restart the PC : http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe
Run McPreinstall tool : http://download.mcafee.com/products/licensed/cust_support_patches/McPreInstall.e xe
Try installation again from your online account : http://us.mcafee.com
At first uninstall McAfee via Add/Remove programs and reboot. Then go to Useful Links at the top of this page and run the MCPR removal tool. MCPR will remove any traces of McAfee that might be left behind that Add/Remove did not take out and reboot again.
See this document for further information and be sure to run the McAfee preinstall tool that is included in the document http://service.mcafee.com/faqdocument.aspx?id=TS100119
Try to install again and let us know if still need more help
Thank you both for the advice. I think the windows automatic updates was causing McAfee to freeze (the updater was trying to install a very old, unsupported update), as I cleared my temp data and some other things and the updater starting functioning properly and McAfee was able to process to the incompatible program step, and I followed Dinz's steps for clearing Norton and PC-cillin. Everything worked, and McAfee has properly installed onto my computer!
I'm glad this worked out, I've been using McAfee on my other PC for years and wouldn't want to resort to other security systems.
Thank you again.