When comparing two strings in a case insensitive manner, use:
myFirstString.Equals(mySecondString, StringComparison.InvariantCultureIgnoreCase)
or, if cultural rules are to be ignored completely* then use:
myFirstString.Equals(mySecondString, StringComparison.OrdinalIgnoreCase)
over:
myFirstString.ToLower() == mySecondString.ToLower()
* The invariant culture is actually a non-region specific English language culture. The ordinal comparison is faster than any culture specific comparison as it uses a much simpler comparison algorithm.