These are created by SiteAdvisor and McAfee is aware of the fact that they should be cleaned out automatically. Fortunately they are all small in size.
There are two methods to try.
The first use Disk Cleanup via Start/Control Panel/System and Maintenance - "Free Up Disk Space" or similar. I'm in Windows 7 beta right now but the location of the utility is similar. Make sure you have selected Temporary Files for cleanup in the list.
The second method is more complicated.
Restart PC to "Safe Mode with Command Prompt" by tapping F8 repeatedly at reboot and then selecting that option from the subsequent menu. At Command Prompt type "attrib -h -s -r c:\windows\temp\*.*" without quotes, Enter. Then type "del c:\windows\temp\*.*" without quotes, Enter. The files should be gone, if they are files, not folders.