The value of a ssd is negligible access times giving fast random access. That is what the OS does mostly.
Yes, you will see faster boot times with a ssd, and everything will feel quicker.
Sata 2/3 is a non issue. It is a minor issue if you have several ssd's in raid-0 doing sequential operations.
Even with a single ssd, sequential operations will be faster than any Hard drive.
The only issue with a ssd is limited capacity and greater cost per gb.
The 60gb ssd will be enough for the OS and a few apps. You will have to use the hard drive for storage once it gets filled.
At $50, that is a good price for a ssd. Get two.