A question regarding updates

[Natalie]

I finally got my Mac on the net and was looking at the software  
pdates, and I have five of them.  I got one for quicktime, and of  
course ITunes and there was one for Mac os 10.55 and two other ones I  
can't remember.  Are all these okay to install?  Sorry for all the  
questoins, I'm still new at the Mac so don't want to mess anything up.
Natalie