I have checked out a project using Subversive for Eclipse and I am getting the following errors:
Indeed this problem is to be fixed under Preferences -> Java -> Installed JREs. If the desired JRE is apparent in the list - just select it, and that's it.
Otherwise it has to be installed on your computer first so you could add it with "Add" -> Standard VM -> Directory, in the pop-up browser window choose its path - something like "program files\Java\Jre#" -> "ok". And now you can select it from the list.