Sorry we didn't get to you sooner, I haven't been here much in the past few weeks..
according to MSDN.MICROSOFT.COM The memory limmits shown for windows 7 versions are as follows..

windows 7 starter
32 bit 2GB
64 bit 2GB

windows 7 home basic
32 bit 4GB
64 bit 8GB

windows 7 home premium
32 bit 4GB
64 bit 16GB

windows 7 professional
32 bit 4GB
64 bit 192GB

windows 7 Enterprise
32 bit 4GB
64 bit 192GB

windows 7 Ultimate
32 bit 4GB
64 bit 192GB