I just ordered an 80GB Intel X25-M SSD for my 2.4GHz Macbook Pro and need some advice. The MacBook Pro will have one SSD and one HDD as I also bought an HDD caddy from newmodeUS which will replace the optical drive. I'm planning to put the OS and applications on the SSD and data on the HDD. As I don't fully understand how SSDs work, I'm worried about possible performance degradation over time. If I, let's say, have 20GB free space left on the SSD, and all these blocks are "unused and free". I then copy over 5GB of data which I then delete. Now I have 15GB of "unused and free" space and 5GB of "used and free" space. Which of these spaces will the next 5GB file I copy use? In particular I'm thinking about my VMWare Fusion virtual machine running Windows. I'd like to have it on the SSD for quicker boot times but I am worried that excessive writing to disk will slow the SSD. And what about Safari cache? Should that be disabled or moved to the HDD? Any settings in OS 10.6 that should be changed? Since the SSD is only 80GB, I will have a difficult time not filling it. For best performance, how much space should I aim for leaving free? If the SSD slows down eventually, will a re-install of the OS make it "new" again? Thanks.