That isn't the problem, Jack. Android SDK isn't x64, but works ok with x64 jvm (and x64 eclipse IDE).
As helios said, you must set project compatibility to Java 5.0 or Java 6.0.
To do that, 2 options:
"Android Tools -> Fix
Project Properties"
(if this din't work, try second option)"Properties -> Java
Compiler"
, check "Enable project specific settings" and select
1.5 or 1.6 from "Compiler compliance settings" select box.