Thanks to this tutorial, I was able to upgrade my Mac Mini media server to 3GB of RAM. That allowed me to upgrade it to Mac OS X Lion as well (it only had 1GB before, and Lion requires 2GB). That’s made quite an improvement in file sharing responsiveness. If you recall, even on Snow Leopard, it could take 30 seconds to connect to a server. Initially, I had tried to use the DIMMs left over form my MacBook Pro upgrade (to 8GB), but they were too advanced. Luckily, I had an old white MacBook in the closet with a bad motherboard which happened to have matching DIMMs, so I was able to complete the upgrade.