You can still manually download the defs files for SE from:-
http://www.lavasoft.com/support/securitycenter/blog/(the link is at the top right of the page)
Fine if you're using XP, but they haven't worked with 98/ME since mid May. There were many of us in your situation a few months back, and the conclusion of the debate that ensued was that the only option for up to date protection was to move on to another product (even amongst moderators!!). The 2 products that still support 98/ME that most people moved on to were:-
There are a few more products out there that also support 98/ME (and quite a few bogus ones, so be careful!), but the above two appear to provide the best protection. I've been using SAS for the past few months, and it's an excellent product, although I'll probably switch back to a Lavasoft product in addition when I finally get my new machine!!
Take your pick!!