hard disk slooooooooooow and making odd noise

[Deep]

hey ive had this pre built pc for a while now, (prob 2yrs).
recently i formatted the computer and since then it has been a lot slower,

eg. playing a song in itunes makes the song jump and the computer freeze for a few seconds

im gonna phone the company up on monday, but does this actually sound like a problem with a hard disk problem

 

[Deep]

like a crackling whirring noise, not like the normal noise at all.