It's about as simple as you state it, Heather: White's first move confers the initiative to her/him. That initiative can last - in some opening lines (think Ruy Lopez) - in 20+ moves or more. Indeed, White typically scores 55% to 45% versus Black in most of the mainline openings.
That being the case, Black has her work cut out for her. Some say she must first try to equalize before taking any drastic action. Others say that she must imbalance the position to make the initiative less of a factor. In any case, the majority of chess players find it more difficult to deal with the Black pieces. This might explain your statement: "... new to chess and generally play white."
GM Adorjan has written a couple of books on the subject (His latest: http://www.amazon.com/Black-Forever-Chess-Andras-Adorjan/dp/0713489421).
Don't be afraid of Black. In fact, some people prefer to see White's attack crash on the shoals of their great defense, then put White out of his misery by dispatching his king in a counterattack.
Good luck.
What are the differences in playing black or white? Bar the fact that White always starts, are there any other differences?
Just new to chess and generally play white, can anyone tell me the advantages/disadvantages of each colour and any differences there are between the two?
Cheers
Heather :)