For interviews, wear a tie. Unless you are applying for any of the following:
1) CPU designer (in which case, don't even bathe)
2) Game engine designer (in which case, be sure your tatoos show)
3) Game level designer (in which case, make sure your piercings show)
4) Kernel developer (in which case, blow off the interview, email a sample of your latest Linux patches, show up for work next Monday and expect to sign a contract).
All others should wear a tie - which you can ALWAYS make slightly humourous remarks about if they (highly unlikely) razz you for it...you can always say your gf made you, for example, if it is obvious they think you are overdressed. "You know women..." said with a smile always works...
Future Shock