Like Gail said, SQL Server rarely throws "out of memory" type exception. If low on memory, it will typically spool to tempdb, or if there are simlultaneous requests, will start suspending processes. It will do everything it can to execute and complete a query, even if running on an underpowered server and under extreme memory pressure. What you will find in that scenario is that queries simply run for an extremely long time, rather than aborting with a memory error.
So, confirm if the issue could actually be users selecting large resultsets down to their query tool or application. For example, I know SSMS will give out of memory messages, if GB of data are dumped into the result grid.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho