It's quite common for software to be 64-bit compliant but not actually 64-bit, hence Windows having that x86 folder. My installation is exactly the same as yours in 2 Vista Ultimate SP2 x64 rigs and 2 Windows 7 Ultimate RTM x64 rigs.
My x86 folder is packed with a whole host of software.
If your software is malfunctioning or failing to install properly then I suggest the following:
1. Uninstall all McAfee programs through "Add or Remove Programs" in Windows "Control Panel".
2. Use the MCPR tool, see this article: How to remove supported McAfee consumer products using the McAfee Consumer Products Removal tool (MC...
This will remove all McAfee remnants from your computer. (you must have Windows 7, Windows Vista, XP or 2000 SP4 to use this tool)
If the tool indicate incomplete removal, reboot and re-run it.
3. Launch Windows Explorer and delete all McAfee files in "Program Files" but especially in "C:\Document and Settings\<user>\Application Data" and "C:\Document and Settings\All Users\Application Data". You have to set Windows Explorer to show all hidden files and folders (Tools > Folder Options > View tab). Just delete the McAfee folders even if they are empty in all the "Application Data" folders. Can be more than one!
In Vista/Windows 7: C:\Program Files, C:\ProgramData and C:\Users\yourname\AppData\Roaming
If you can't find these files don't worry. It just means that MCPR has done its job.
4. Reboot and redownload/reinstall your McAfee products directly from your account at the McAfee web site.