I use Zipslack within my Windows 98 "C" installation on an ancient (built in 1995) P150 computer with 96 Meg of RAM. It runs great so far. I use ZipSlack 7.1 on this thing because it is the best thing for that particular machine.
I have to use Slack 7 because this old machine sports a Diamond Stealth 64 VRAM graphics adapter and the architecture won't support anything newer.
ZipSlack can be made to run all 2 GB of the Slack distro, you just have to install them in the proper place. It works great.
only use a windows-based unzip utility like Winzip
Unzip it into the regular C:\ drive not in C:\Windows.
From regular DOS-mode change into C:LINUX\
then type "linux" or "linux.bat"
If you had hardware that doesn't fit plain vmlinuz, that could be a problem also. There is info on that isue in the FAQ -- just replace vmlinuz with one of the appropriate kernels for your hardware configuration.