I have one very last Debian host running "testing" that I keep as a development platform. The computer in question is an aging ThinkPad 240x whose LCD cable constantly threatens to make the display content unreadable and whose non-expandable 192MB of RAM is ridiculously small by today's standard. On the plus side, this makes for a very small development host that I can easily tuck away in the closet whenever I don't need it.
However, one problem currently plagues this computer: it has been through literally years of dist-upgrades and it has accumulated TONS of cruft on its filesystem, namely files that, according to packages.debian.org, should not longer ship with the packages "dpkg" claims they belong to but, for unknown reasons, nonetheless remained on the system, probably as the result of botched upgrades whenever package X had broken maintainer scripts during the development phase before "testing" was frozen and moved to "stable".
Making a clean install from Lenny could be a nice solution, but doing so on a laptop that has no CD-ROM, whose BIOS has no support for USB boot and whose only other boot option is an external 3.5" floppy disk drive, might prove more tricky than I'd bargain for (Google "ThinkPad 240x" and you'll see how tricky I mean).
I am thus wondering if anybody would know of any tool capable of comparing files present on the filesystem with those stated as shipping with packages matching versions currently installed, according to files lists found via packages.debian.org, so that I can at least sanitize the filesystem and restore the content to a fresh Lenny install state?