<p>We have SQL Server 2005 running on Win2003/64, and we push it hard.  We generate real time reports on several tables with a couple million records using asp.net 3.5, and they will periodically time out.</p>

<p>I'd like to increase our memory from 8GB to 16GB or even 32GB to see how that helps, but I need to justify this to the pencil pushers before they will spend the money.  Can someone point me to some resources that will help me make my case and will get me some hard numbers to use?</p>

First find out what is really the problem and that the server is properly tuned for the queries you are running. It's very sad to waste the money on RAM to find out you are I/O bound.
After you gather data about the cause of the timeouts you should be able to convince the pencil wielders easily.
Some tuning/monitoring links:
http://www.brentozar.com/archive/2008/03/sql-server-2005-setup-checklist-part-1-before-the-install/
(check both articles)
http://www.sql-server-performance.com/
About I/O specifically:
http://www.microsoft.com/technet/prodtechnol/sql/bestpractice/pdpliobp.mspx
http://searchsqlserver.techtarget.com/generic/0,295582,sid87_gci1307990,00.html
http://www.novicksoftware.com/Articles/sql-server-io-statistics.htm