My inbox has been filling up with emails from ESRI about the Beta testing program for ArcGIS 9.4 (now 10). So I finally downloaded the new version. But I was wondering if I can keep my 9.3 installed while I take a look at 9.4. Maybe I didn’t have to download the 3GB installer after all because apparently you cannot. I found the answer on James Fee’s blog in a discussion thread that included some very interesting comments about ESRI’s aging technology.