Hello. I recently restored my stock iMac early '2011 21.5in with the core i5 at 2.5Ghz model to the latest edition of Snow Leopard. I'm glad I did as Lion truly was a system hog. My boot time alone was worth it. OSX 10.6.8 boots up in a matter of seconds while Lion would hang for nearly a minute. My RAM memory usage is also much better. Lion with no applications running would only leave me with about 1.7GB of free memory. Snow Leopard with no applications running leaves me with a little over 2.4GB of free memory. I'd like to keep the speed increase, but I'm afraid that if I start migrating my media onto the internal HDD my read/write speeds will start to slow. On to the question at hand. Would keeping the OS on the internal HDD while putting everything else on an external USB 2.0 HDD allow the overall speed of the system to remain in tack? I understand that accessing information on the external drive would be slower, but so long as it's nothing drastic I don't mind.