Looking around on the internet I discovered that by default Snow Leopard boots into 32bit kernel mode (I wondered why I wasn’t getting any incompatibility issues) and to force OSX to boot into 64 bit kernel mode you need to hold down the 6 & 4 keys on startup.
I tried this out and it worked I confirmed this by going to System Profiler and checking whether 64 bit kernel mode extensions were loaded.
I thought cool maybe 8GB RAM will work now I have booted into 64bit mode but I wanted to try out all my critical applications first because theres no point having 8GB RAM if I can’t run any of my programs. One of my most critical applications is VMWare Fusion which threw the following error message when I tried to open it.
Looks like VMWare doen’t support 64bit OS X yet so I won’t bother trying out the extra 4GB module yet as there is no point if I can’t run VMWare.