Support for Windows 98 was supposed to end in January, but Microsoft has extended that. I check out Windows Update once or twice a week. Admittedly, updates for 98 are much more infrequent than for XP, but just a few days ago two critical updates appeared.
My ISP notifies me via email of certain updates available, too. Now and then Microsoft releases something that is not included at the Windows Update site. Usually these are updates geared to very specific vulnerabilities that most folks won't need, but I like to get them anyway. Even if only for the fact that it's something FREE from Microsoft! I'm not a Microsoft hater, though -- I'm quite fond of Windows and can't wait until I can afford a PC that will run XP. I only get to work with it these days at customer's homes...
Speaking of clock synch -- here's another nifty freebie:
http://www.worldtimeserver.com/
I do NOT let anything run in the background or load itself into the tray area, but this is nice because you can also just disable the auto-start features and fire it up if you notice your clock is off. Some programs seem to enjoy fucking up my clock. This is a handy tool which synchs up with World Time Server.
Never had a problem with Outlook. My ISPs web-based email has spam filters which simply never let the junk get through to Outlook. You can also set Outlook to refuse dangerous attachments, but this can lead to missing certain files you actually WANT.
To each his own, though. I always tell my customers their PCs should be friendly to them and be set up in whatever way makes them happy.