On what release version is/was your old site? If your site is technically a plain simple gallery site (without much custom stuff or not yet included official themes or plugins) the chances may still quite good that you are able to update to the current release or at least in some steps. There might be a bit works that should be noted in the logs.
Complicated sites (like our own site that except the forum and docs is also ZP) will likely cause more problems.
I did successfully update old sites from 1.0.x to 1.4.x. But that of course might just have been luck ;-)
Perhaps worth a try maybe since the mentioned backup tool and XMP does not exist in very old releases but of course backup first ;-)