When I read the first page of this thread, I jotted down a few ideas.
I see some of them have been explored on subsequent pages, but here they are for what (little) they're worth:
1). hook up a CD burner to the DOS machine.
Sounds like most of your files would fit fine, and you'd have a nice backup library of anything transferred.
2). if you can go the FTP route with a card in your old machine, then
Cerebrus FTP server is Free for personal use and would run on your XP box.
3). back in DOS days , I had batch files which managed how I booted.
I had entire boot configuration libraries which could be invoked by a simple command.
The short version is, I could boot to DOS, with a scanner drive, with max memory, to Windows 3.11 with LAN support, etc.
So, if you don't mind the rebooting (even make it simple by booting with a floppy), then use Win 3.11 networking to pass the files.
4). You are running on a PII, and say that system is "faster".?
Only after I read farther did I discover how you had customized the old system.
I've participated in projects or jobs where we moved data from one type of system to another, or upgraded the system tremendously.
Generally, the best solution is to move your tools to the new platform, and if in this case it means your custom Lisp, so be it.
A new computer with something like an Intel Core 2 Duo e6600 (two cores), will so blow away your P2, you'll wonder why you waited.
Most likely, the q6600 or similar four core cpu wouldn't give a great gain.
Of course, it wouldn't cost much more, either.
Sorry if #4 (get a big computer and move on) seems cold, but in the end that's probably the best solution.
I both
have and
support old systems, and they do eventually die.
What will you do when that happens?