If you end winlogon.. Your going to screw up your Windows attributes. Since it supports many, I mean many of the user related proccesses that are very much needed.
winlogin is another story. That is the malware. Unless it is winlogon.exe.
A few examples of what logon does, and why it is a sweet terget for malware.
logon logoff
User Profiles
Network support
User shell access{acess for user permissions)
The most important WGA.. if your legit.
Pretty much if you have a User in NTFS, winlogon is the base for it.
If you have done some dumb fileshare. I mean opened idiot type files in fileshare. You need to evaluate your habits and then take action. If your clean, then your all good. For the most part. Run a online scan. If your totally still not convinced. Reload Windows.