I suppose you used the 'create boot disk' icon in the system group in Yast2. (I'm translating the German terms, so it might be a different name.) That's not how I did it, I got the same error actually when I tried that. I have no idea where those images are supposed to be.
Here's what I did: next to the aforementioned icon there is one with a sneaker shoe saying 'Configuration of boot loader'. I'm supposing it's LILO. In the menu, choose /dev/fd0 as 'location of boot loader'. In 'available entries' make sure something points at your kernel (e. g. Label=Linux, Type=Image, Image/Device=/boot/vmlinuz (/dev/sda1, root=/dev/sda1). Your actual entry may vary, especially if you don't have SCSI disks (hdaX instead of sdaX).
There should also be an entry for your Windows such as 'Windows ; Other ; /dev/hda1.
There may be more, for example 'Failsafe', but that needn't concern us now.
Set the standard to the entry you'd like to boot automatically when you don't choose anything else from the menu you get. I suppose you can leave all the other entries as they are.
If you then proceed with the dialogue I expect that you'll be prompted for a floppy disk, and the boot loader will be put on it. You might have to set your system bios to boot from floppy first (before hard disk) if that's not the present setting, but you should be able to boot at least your linux this way, maybe even your Windows if you haven't killed it and you give the entry the correct device (hard disk) where its boot block is located.
Hope that helps,