It is usually more work than most want to fool with..... you have to wipe the entire hard drive clean.......and create a small partition.... say 1 gig......then format it fat32..... then load win 98. Once 98 is up and running.... you can load vista from scratch..... creating a second partition that is usually the rest of the hard drive......and installing Vista on this partition.
FWIW... I've never done a Vista/98 dual boot but it should work the same as XP.....but I can't confirm.
You will need a parallel port on your laptop.... which apparently a lot of the newer laptops do not?
If all this sounds like too much work.... you can try powerlogger..... it doesn't need a parallel port or Win 98..... it will run on the newer operating systems.
Hope that helps.