Using a external HD to store music

So ive been retagging and Keying all my tracks so i can sort through them on the fly while I play my sets. Im using smart playlists through itunes and I would like to use itunes as my base for organizing my tracks.

My question is, I noticed a lot of people keep their music on a seperate external hard drive so that the cpu doesnt have to process all the data. How would I go about doing this so that it loads in itunes properly when i plug my harddrive in and get rdy to play a set?

Is this something you guys do? or do you just leave all your music on your hard drive? I know an SSD would be a great solution but I dont want to spend all that money right now.

Thanks

Keeping media in an external drive doesn't save the CPU any load. The main reason to do so is for increased storage capacity if you have a small internal drive, second would be portability.