I have Java7 running on 32-bit Windows and 4 GB RAM, but:
java -Xmx4G -Xms4G -jar Minecraft.jar java -Xmx3G -Xms3G -jar Minecraft.jar java -Xmx2G -Xms2G -j
Double click Liferay CE Server -> add -XX:MaxHeapSize=512m to Memory args -> Start server! Enjoy...
It's work for me!