There should be no problems, I have a similar setup in part. Just make sure you put your network behind a router.
One thing to watch, Win98 default name for the home workgroup is WORKGROUP, XP uses MSHOME. Sometimes I have to work hard to convince XP to use the name WORKGROUP as it seems to change itself back to MSHOME every now and again. Would probably be easier to rename it MSHOME in 98 but I have a problem with that as I refuse to have MS in the name. Besides I like being bloody minded!