This does not effect modernSSD.
FTFY.
60GB SSD sounds by its size like an older modell and might actually still have that issue.
About the 60GB in general: Due to the way SSDs access/allocate the data, they reserve a hardcoded part of the capacity for themselves, not allowing user access to it. So, whatever capacity is advertized for the SSD, it's normally somewhere between 5-20% less. Keep that in mind.
I believe there was something about block sizes and SSDs meaning that a big file takes more physical space than the size actually would suggest but I can't remember anymore and I am too lazy to re-read it
One last suggestion:
If you're running a legit copy of windows 7... Switch to windows 10. It's smaller by a good margin and at least as good as Windows 7.