98SE is an okay O/S - I use it sometimes on a spare PC simply because I have a copy of it (and it refreshes my memory of blue screens!)
2000 is my preferred choice - and I also do a fair amount of DV editing. O/S is as solid as a rock - never locks/freezes/crashes.
XP is (remember folks this is just my opinion) 2000 with bells and whistles added. It tries to "best guess" what you will want to do when you add hardware/software etc. All these features can be turned of (saving power for what you really want it for) but once turned of you have the 2000 O/S.
If you own 98 and its working for you why change?