I have an Acer Aspire with two hard drives, can I...

Its not two hardrives, its duo processor, and two cache chips

check the size of data and acer drives (right click and properties, check size)
If they are large should be able to store copy of music

go into the limewire download folder, should be in my computer -> c: -> program files -> Limewire -> shared folder - copy files (edit select all, edit copy or ctrl + left clikc to individually select)
then paste to new directory or folder (right click empty sapce of folder & left click paste

same for Itunes - locate where files are saving to then just copy paste from one location to another

should effect the programs from working, unless You delete files