Oh comeon Sandeep. Don't be a kid. By the way, i need to correct your English (Should i say Ninglish :-)). The spelling of the name of a person is not fixed and this is an acceptable thing both in U.S aswell as in U.K English. For example, Mark is sometimes spelt as Marc. Also, it's not written at any recognised place (Oxford or webster's Dictionary) that the spelling of Sujatha (yes, i'm a south Indian) is wrong.
Let me also explain a reasoning behind this. There are 2 sounds here 1)th:- as in Sou'th', Nor'th', 'Th'orium, 'Th'row. 2)t :- as in 'T'asmania, Complica't'e, 'T'oma't'o, 'T'elegram.
It's up to you to decide which sound is more appropriate for Sujatha.
Moral:- Blame the language (English) for having such inconsistencies and not Indians (forget South/North).
