Fonts in Netscape

I find that when I save certain web pages (NS 7.2; File|Save Page|Web 
Page-html only)the page gets saved.  But when I then open it using Windows 
Explorer it opens (in Netscape, I believe) but the fonts are not the same. 
For example, if all the fonts in the original web page were sans serif they 
are now Times New Roman.  As a technical matter, this means that the page I 
saved is different from the original; if I tried to represent it as the 
original I would not be believed--because it doesn't even look like the 
original.  Moreover, the font change actually screws up the document's 
readability.  In this particular case I want to save the web page showing a 
month's worth of financial transactions.  In the original font, all the data 
line up in their columns and the whole this is easy to read.  Change the 
font, though, and it isn't easy any more.  Is there something I have to do 
to, well, save the web page exactly as I see it on my computer screen?