What purpose do you need to quiet the drums? Is it for practicing? Is it for recording?
If it is for practicing, then you can get a set of "Sound Offs" which are pads that are placed over the drumheads and seperate pads for the cymbals and kick drum. They make the drums sound like crap, but will allow you to practice without disturbing neighbors and family. You can also get a set of mesh heads to use on your set for practicing. They're absolutely silent to the touch, but if you ever want to get a drum sound, you then have to replace all the heads again with real drum heads.(a real pain in the ass)
For recording and controlling bleed into other instrument's mics, you'll need to built an isolation room, (expensive) but there's no other way. A drum sheild will only help to a certain extent. If the room is small and resonant, you'll need more isolation than a sheild will give you. If you're not worried about sound leakage into other rooms, then you only need to isolate the drums from the other instruments, Otherwise, you'll need to build a room within a room just for the drums (check out this topic on the studio construction forum below).
Treatment of the interior of the room whether you build a seperate isolation room or not is critical for getting good sound when recording. You'll need bass traps, bafflers, acoustic foam, padding of all sorts which can include hanging carpet or quilting, cushions up against corners and reflective surfaces, etc.
I knew little about this a few months ago, but I've been involved in creating an iso room for my own drumset the last few months and I've gotten much good advice here and on other boards, done tons of reading and a lot of trial and error. It's pretty good now, but there's always room for improvement.
Good luck.