I think e1-570g has only SATA2 but it is not a really a problem if you would like to use an SSD with SATA3.
Any SATA3 HDD or SSD are backwards compatible to SATA2, it is only that they will run with SATA2 speed.
Like said above, SSD can not give you more fps and only give you faster loading time like map loading etc. etc. in games.
Loading time is the key, it goes not only for games OS booting will be a lot faster, opening programs will be a lot faster, etc.
SSD is still one of the best upgrades you can get for computers nowadays especially laptops.
SSD consumes less power and more physical shock resistant.
If you can afford it, I would recommend to get an SSD.