I'm not sure what the problem is. Do you have lots of incomplete albums containing only the occasional song or do you have full albums? That has bearing on what kind of database you can use to get your information.
If you have incomplete albums and need to find metadata for f.ex single songs, then I think you could use a tagger that scrapes info from
musicbrainz. You might also use gracenote which comes with Winamp. There may be easier ways to do it, but using the Winamp way, you'd just install that media player, load in your library and auto tag your songs.
I personally like the
discogs (I like their standardized genre/style system), but my software only queries it for albums and not single tracks. It's also not the largest database.
edit :
The tidiest way to keep a music library is not to enter anything into it until it's been properly tagged.
another edit :
If you're a foobar user, there is a musicbrainz tagger ->
http://www.foobar2000.org/components...oo_musicbrainz
There's also a very nice discogs tagger (very!), but I guess it might be less useful in your case.