I recently picked up a Mid-2009 White Macbook as a back-up for my main computer, a 13" Macbook Pro. The price was cheap on this system, and it had some great software pre-installed. It also has 4gb of RAM. I upgraded it to Mavericks, and then to Yosemite public beta(to get familiar with it before the final version comes out and upgrade my main machine), and noticed that the installations of both took a fairly long time. It also seems to bog down a lot when doing things that involve a lot of read-write operations. SMART Utility identified several bad sectors, and identified the drive as "failing." So, with that in mind, I think I should replace it sooner rather than later. I'm basically debating between two options on Newegg, both at about the same price point. I can either get a WD Black 750gb 7200rpm HDD, or a Sandisk Extreme II 120gb SSD. Both are a little under $70. I could also get a 128gb Sandisk UltraPlus for $60. This is about the maximum amount of money I'd like to sink into this system. The extra capacity is not a big deal-as I mentioned, it's not my main computer and I also have lots of Firewire externals to use if I run out of space. I never mind the extra space, though. What I'm wondering is how much of a performance difference I'd see in this particular system when comparing an SSD to a higher end HDD. I'm thinking specifically in terms of boot time, program launching, and general "snappiness" of the OS. Also, I know that some older Macs(I'm thinking specifically of the G5s I still play with a lot) have issues with SATA III drives. Does this same limitation exist with the Macbook?