The bug report does not really fit into this scenario, as it is clearly linked to mobile, has been fixed and occured in a very old version of Unity which we are not using. Also, we can't try out the workarounds from the thread because they don't apply to our setup.
We suggest on your Win7 machine you should try the 4GB-Tuning (BCDEDIT /Set IncreaseUserVa 3072) or PAE (BCDEdit /set PAE ForceEnable). We cannot help with the crashes on XP, though.
Also, we are preparing an update which allows you to reduce the scene cache size. That may help, too.