VersionLimit in 32-bit WindowsLimit in 64-bit Windows
Windows 7 Ultimate

4 GB

192 GB

Windows 7 Enterprise

4 GB

192 GB

Windows 7 Professional

4 GB

192 GB

Windows 7 Home Premium

4 GB

16 GB

Windows 7 Home Basic

4 GB

8 GB

Windows 7 Starter

2 GB

2 GB

Windows Vista Ultimate

4 GB

128 GB

Windows Vista Enterprise

4 GB

128 GB

Windows Vista Business

4 GB

128 GB

Windows Vista Home Premium

4 GB

16 GB

Windows Vista Home Basic

4 GB

8 GB

Windows Vista Starter

1 GB

Not applicable

Windows XP

4 GB

128 GB

Windows XP Starter Edition

512 MB

Not applicable

 


References:

http://msdn.microsoft.com/en-gb/library/aa366778%28VS.85%29.aspx