No, 32bit applications can not use more than 4gb, even when ran on a x64 system. I personally found that running x86 apps on an x64 system is more of a hassle than it should be. And not to mention the translation needed to be done by wow64 could introduce problems. I would personally stay in the x86 system until everything runs in x64 natively... D!J!X! _____ From: ddots-l-bounce@xxxxxxxxxxxxx [mailto:ddots-l-bounce@xxxxxxxxxxxxx] On Behalf Of Chi Kim Sent: Thursday, November 26, 2009 10:33 AM To: ddots-l@xxxxxxxxxxxxx Subject: [ddots-l] Re: Ct8.5 and 64Bit? I thought an application can address more memory when the application is 64bit and running on 64-bit os, not 32bit running on 64bit os. Am I wrong? Therefore, you have to run 64-bit Sonar on 64-bit windows to take advantage. As far as I know, ct can't run on 64-bit unless David rewrite something. _____ Windows 7: It works the way you want. Learn more. <http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WL MTAGL:ON:WL:en-US:WWL_WIN_evergreen:112009v2>