depends n what you are doing
if 'all' you are doing is maintaining a list of PDF's, their price, location and a brief description etc then you don't need a db.
you could store that information in an Excel file, heck you can even store it in a flat file, depending on the complexity (or number) of PDF's you could do it the old fashioned web way and put it as part of the web page, bypassing nay intermediate storage mechanism
But if you want to offer search capabilities, or grouping, or indexing or brief precis eg a the index of the PDF, or a significant chapter then you are starting to get into the realm where having a db may well be a smarter move.
norie is correct in saying the Excel is a spreadsheet nto a db, but depeninding on how complex the data is (or more accurately isn't) it may be good enough for your purposes. You don't need a relational db to solve every systems problem
Not knowing what your data is, and how complex it is I suspect that stroing in Excel is perfectly feasible. Depending ont he number of different PDF's you have (say 20..100) then avoinding exteranl storage may be perfectly acceptable depending on your skills and time available. Like most things in life its a trade off.. if writing data driven websites uisn't your forte it may be quicker and cheaper to do it by what db developers would call the hard way but html.
I think the potential stumbling block in my mind is using frontpage. I looked at a much earlier version of Frontpage, and though it appalling.