I don't know what GRUB is, but it all sounds good enough to me. Just wondering why 3 Linux partitions when you can get away with 2 (one Linux formatted, one swap), or are you trying to seperate the system from your data like that?

EDIT: Oh, and you'll find Win98SE can live happily on a 1 GB partition, the OS itself shouldn't be over 200 MB or I'd be worried - the rest can be swap/temp/whatever So a half-half split may not be the best distiribution for the OSs I'll assume any programs and data 98 will want to use can sit on the XP drive, unless you've done that NTFS or something