We were having trouble with a MOSS 2007 upgrade in that it was throwing out of memory exceptions that are common with ASP.NET applications that are running on a server with more than 2 GB of RAM, but the application consumes it all. See http://support.microsoft.com/default.aspx/kb/820108 for details. The fix in this article is to apply the /3GB switch and optionally the /USERVA switch to allow applications to utilize more than the standard 2GB of RAM.
For a sample boot ini, see this article and below:
[Boot Loader] Timeout=30 Default=multi(0)disk(0)rdisk(0)partition(2)\WINNT [Operating Systems] multi(0)disk(0)rdisk(0)partition(2)\WINNT="Microsoft Windows Server 2003" /fastdetect /3GB /USERVA=3030