Dispite there being only a 32bit version of the android SDK, you can still work with it on your 64bit machine, make sure you have the following packages installed:
Debian, Ubuntu, etc
apt-get install ia32-libs apt-get install sun-java6-jdk
Fedora, CentOS, etc
yum install glibc.i686 zlib.i686 libstdc++.i686
Download the 32bit SDK
(If link is dead see Reference)
Extract and change into the newly created directory and run tools/android update sdk –no-ui.
This will start updating everything in the SDK – Note this will take a while.
You should now be ready to start developing.