Update! October 2012
Finally, the Windows 98 files needed to install FrontPage Express are... gone from Microsoft's site.
Zip. Nada. Gone.
You may want to check out this instead: Mozilla SeaMonkey SeaMonkey is an all-in-one browser, email client, NNTP news client, IRC chat, and a very good HTML editor, completely free.
What's Better than FrontPage Express?
Microsoft is providing Visual Studio Web Developer Express completely free, and it makes FrontPage Express look like a kid's toy. You should get it instead.
Can I Still Get FrontPage Express?
No. Microsoft removed all Windows 98 files from their web site, per their product lifecycle plans. Sorry. If you find it anywhere else, it's probably of questionable legality.