I think I want to try to do is load one of the primitive versions of Linux onto a flash drive and boot my primitive computer from the flash drive.
Again, I'm sorry to be full of doubt, George. There is a more than good chance that your old Dell will not boot on a USB flash drive. If I have found the correct service manual (see below)... your Dell originally shipped with Windows 98, although you may have upgraded it to Windows XP. The manual indicates it should have a CD-ROM... and that means it is likely a read-only device, and not a CD burner (so that you could burn a Linux disk on it).
Look in the Dell BIOS Setup to see if USB is an available option in the Boot section.
The Windows system that currently boots the computer (XP I believe)
If it is still Windows 98, that system used to require special drivers to access a USB flash drive. If it is XP, it may have drivers built-in to access the USB, but I'm not sure. Have you ever used a flash drive on this computer... recently? If you plug in a USB flash drive and can read/write to it, I strongly recommend that you save your RTF and PDF files (and anything else important to you) to the flash drive and move them over to your modern computer for safe keeping. If you later "burn" a Linux distro to a USB, it will erase everything on it, so be careful not to lose your files by leaving them on the same flash drive.
Modern Linux can open both RTF and PDF files, but you may need different programs... very possibly programs that will not be available on the version you need to run on the Dell. This isn't a big deal. The big deal is just getting you on Linux, and how to do that. I would again recommend against spending time (or money) on the old Dell, except to retrieve your important files. If the Dell is indeed a Window 98 vintage... it is just not worth the effort.
If you insist on trying, and if your Dell BIOS shows you can boot on USB, you can use your modern computer to burn a 32-bit Linux to USB (Tiny Core Plus, or other, but be sure it is 32-bit). Don't try to install Linux to the hard drive until you have saved your files, or they will be lost.
If your Dell BIOS does not show a USB option, do you have a CD/DVD burner on your modern computer that you can make a Linux CD instead? And maybe a few blank CD's to test with? DVD's will not work. CD's should be CD-R or CD+R and not CD-RW type. Each Linux distro you would try will need it's own CD and will not be usable again for anything else. Booting Linux on a CD will not let you copy your files back to the CD, but it may let you access the USB port so that you could copy there.