I bought the Time Capsule as a file storage device. Since then, I have learned the error of my ways - you are supposed to use it as back-up to your main file storage and as a wireless router. But it does the job for now, until I decide to purchase a separate drive and back that up to the Time Capsule.
I noticed that the top surface of the device was quite hot, and online research revealed several reports of the Time Capsule overheating and malfunctioning after about 18 months - which would be just out of warranty. So I have bought a separate USB fan from Amazon for less than a tenner. It takes up a USB slot in the back of the iMac but more importantly, it doesn't take up a precious space in the plug extension lead on the floor. It's made of plastic and is small enough to sit on the desk behind my computer, pointed directly at the Time Capsule and it does keep the temperature down very effectively. It makes a low buzzing sound but it's constant and not intrusive and is certainly drowned out when I play any music or films etc and also emits a smooth breeze onto me while I'm at my desk. When the computer powers down into idle mode, the fan does likewise and then starts up again when you activate the screen. It also has its own on/off switch.
So if you're going to buy a Time Capsule, I would recommend a USB fan, too. basicXL Noiseless USB Desktop Fan