If your going to spend $25+ for a case IMHO you'd be much better off to invest in a new external hard drive and get alot more bang for your buck.
40GB isn't much space now days.
you can get 500gb ones for £60-£100. just depends how much use ud make out of the enclosure. if you can get hold a bigger hdd then it might be worth it
You should get one of those external cases that has TV out plugs, so you can store movies on it, and plug it into your tv, or store music, and plug it into your sterio.