A laptop that dies (the horrible, unrecoverable hard drive grind of death) less than a week after you switch your life over to it is not cool.
Having the old laptop to fall back on is good, unless the reason you were switching to a new one is that the old one was dying.
Having an even older laptop (multicolor iBook, circa the late '90s) around the house as a spare is a good idea.
ld.so.conf won't help you if exim and subversion are trying to use two different incompatible instances of libdb-4.2.so in two different directories and you're using exim and subversion in the same perl process. But then, there really isn't a good reason for exim and subversion to be using different versions of libdb-4.2.so. Cruft accumulates on older systems, but it's easy to clean up.