I have my new notebook - a very nice Compaq nc8430 (very nice gaming box!) with 4GB ram. My first notebook with 4GB RAM. Alas - it admits to having only 3GB which I half expected for 32bit. But turns out (from a colleague) that you might see similar with 64bit dependent upon your components. Want to know more? Then check out http://support.microsoft.com/kb/929605/en-us for all the gory details. I have not yet tried 64bit on it... I think I need a clear day!