I hope I'm not telling you how to suck eggs, its just that its how i over came my problem when needing more space I have 3 hard drives, the third is connected with adapter card in which i can add another to it making 4. If you open up your casing of the tower/midi-tower, you will find you can add more by the spaces left inside. I can fit 6 in all plus the 2 extra from the card. It makes sense to use it when you have so much information in the old (to be) drive.

Smile, your dead a long time :)