Coming to the party late, but just saw the thread.
Part of what you are experiencing is SQLServer will move more and more information into it's specific memory as it operates to improve performance. At the same time you have to have sufficient memory for the server to perform it's other tasks independent of SQLServer.
As was pointed out earlier, each connection also consumes additional memory within SQLServer.
If you have max'ed the memory in your server, Bert will be able to help you set the memory for SQLServer and the server os. One work-around if upgrading your hardware isn't viable is to install a 64/128 GB Solid State Drive(SSD), and create two partitions on it. use a 6-20GIG partition for your paging file (virtual memory), then install version 5 on the otehr partition, with your automated backup going to regular disk/RAID/NAS. The goal is to improve the virtual memory that you can allocate while also increasing performance.
