That's pretty easy to figure out, just pull up your system properties and you can see how much space you have and how much has been used. The first question is whether you actually have insufficient memory or not.
Remove any recent updates and see if that helps. If your computer recently updated, it may be causing problems. The instructions you've been looking at are most likely for increasing the memory Sai is allowed to use- it won't help if you don't have enough memory available to begin with. It's probably not an issue with Sai itself.
