Configuring x64 SQL Server
I often read a number of forum posts concerning performance / configuration issues with x64 SQL Server. I've also found some interesting views on how much memory you can allocate to SQL Server on a x64 install ( I don't have any experience of ia64 - sorry ).
Sort of cross purposes I've been trying to identify paging in x32 systems and I found this KB about x64. There's a note that this KB is currently being rewritten so you might want to keep track of it.
I've also got to add that it appears patching the o/s, which seems to be neglected so often, can help, anyway have a good read of this KB if you're using x64 and performance isn't quite as you might expect.
http://support.microsoft.com/kb/918483