Hi,
Try looking at the ProcessName property:
PS C:\Scripts\PowerShell Scripts\Misc Testing\1-10-2014> $test = Get-Process
PS C:\Scripts\PowerShell Scripts\Misc Testing\1-10-2014> $test.ProcessName.Contains('winlogon')
True
EDIT: If I remember correctly, I believe this requires PS3+ though.
EDIT2: This will work if you only have v2 (I'm sure there's a better way to do this, but this'll work in a pinch):
PS C:\> $found = $false
PS C:\> $test = Get-Process
PS C:\> $test | ForEach { If ($_.ProcessName.Contains('winlogon')) { $found = $true } }
PS C:\> $found
True