Joaquin, I've installed both the 64 bit and 32 bit versions of SAS 9.3 on a Win7-64bit OS.  If you need to interface with 32 bit Office applications or share format libraries with colleagues still using 32 bit SAS, the 32 bit version of SAS is a bit easier to work with. If you don't have to deal with 32 bit Excel (the bane of my existence!), then the 64 bit SAS offers superior performance. Though I have SAS 9.4, I haven't installed it yet as I am not comfortable with it's interactions with Excel in Office 2010. Doc Muhlbaier Duke ... View more