[X4U] lost memory on macbook?

[Mitchell Senft]

I have inexplicably have filled nearly the entire hard drive of my 80G  
MacBook. I admit to 30-odd gigs of music but the rest? The MB is also  
dual booting although the Win side (accessed with Parallels) is used  
to run a remote access to the work machine. Also, when I start up,  
maybe I have 1-2 gigs available and, without saving anything in the  
course of a session, that number shrinks to approximately 500 megs.

What explains all that?

What solutions are there (other than dumping a lot of music)?

Thanks,

Mitchell