I guess my question really boils down to where can an XP user go to get the patches that the open source world has developed?
The easiest way is to do a search for the problem you are experiencing and look at the forums where the problem has been noted and a patch issued, or look for where someone else has posted a question about it or a similar problem.
If it is an older problem you can be fairly certain that someone has already asked about a fix and been answered already.
Sites such as linuxquestions.org are especially helpful specifically for linux, and yes it is primarily a linux forum but they can point you to other sources as they have in the past where there are more windows-specific forums which can help you with the problem(s) if they do not already know what the fix is.
A search is your best bet. Something like “windows xp heartbleed patch” will work best, but be creative in your search parameters.