I finally managed to restore my system.
I first installed the primary dos-partition with ms-dos 6.22 (the only OS I could run, but it didn't support FAT 32). Then I installed win98 on this 2gb large partition so that I could use the new version of Fdisk that does support FAT 32. I deleted the primary partition. Altered the boot sequence so it started with my cd-rom, while my computer kept rejecting my rescue-boot floppy. Put in the win98 cd and it finally formatted my entire harddisk and made one partition of it! I had to format it again and boot from my rescue-disk (which suddenly worked) while the win98 cd was giving error messages over and over again that it couldn't find some files on the cd-rom. A complicated way to format and restore your system...but hé...it kept me of the streets for a while.