Publisher was developed as a desk top publishing program, with the ability to create web pages being very much of an afterthought. (Pages created in Publisher can become very 'bloated' with file content, and take significantly longer to download).
FrontPage, on the other hand, was designed specifically for creating web sites, so it's naturally the better of the two programs.
There are also plenty of free (or very cheap) alternatives available. Serif WebPlus SE is a free, trimmed-down version of a good-quality commercial program, which permits you to create high-quality websites with up to 10 pages. Just �9.99 will get you the full product (WebPlus 10), which offers an unlimited number of pages, plus some very advanced features (such as support for e-commerce):
http://www.freeserifsoftware.com/software/WebP lus/default.asp
Chris