Almost wondered if you were going to give up on this. Great to see you still working hard at it. What I have in my entertainment system is like 280Gigs of mp3's About 54,000 mp3's Loaded on my 400 gig drive . It is directory based ie <drive>/a/ACDC/Live/<song> Etc. If you want i can run your algorythm on it to see how fast it is.
Keep up the good work.
p.s. Isn't C# part of Windows.NET framework? I thought everyone hated .NET?