Quote marks are to explicitly specify 1 string. Depending on how you use them will determine if it works or not. Some DOS commands think that space means 'new argument', so I use quote marks to negate that issue.
i.e.
Lets say I have a file called test.txt in c:\documents and settings
If I had a .bat file that wanted to copy a file from there to whatever directory the bat file were in, I would have to use quotes, because documents and settings has 2 spaces...
Works:
copy "C:\documents and settings\test.txt" .
Doesnt Work:
copy c:\documents and settings\test.txt .
In the Doesn't work example, copy would think i'm trying to copy c:\documents to and - also, it wouldnt know what the heck to do with settings\test.txt
Trial and error at first and then it becomes second nature (as to when to use them, and when not).