someone told me today at work that if you have your guitar setup to standard tuning you shouldn't do different tunings because it will mess up your setup is this true.?
Kind of. Trying to tune a guitar in E standard to Drop C won't work, but just to E flat or Drop D would be fine. It'll mess with your intonation a tiny bit, though.
Dunno....... I change my tunings all the time from standard, Drop C, Drop D, 1 Step Down, 2 steps down and it dont really effect my strings... only that my standard tuning feels tight (Using 9's =/ )
what guitar do you have?
Too tired and lazy to bother with a sig, Sorry.
Really, drop tuning doesnt seriously do much to your guitar, but it can do something. But doing death or thrash metal on a standard tuning setup cant really hurt your guitar. Of course, it sounds better is a dropped tuning. But really, playing different things on your guitar can never hurt it.

I also tune my guitar half a step down for playing other things, and then I tune it to standard for my actuall lessons. Never hurts a thing.
I wouldn't think so, but I keep one in standard and the other a 1/2 step down. This way, it prevents me from having to constantly tune the same guitar between the two tunings.