Haha, I have the same problem. I'd have to check my external hard drive, but I'm definitely into the hundreds of gigs of music area.
I dig sites like Pandora when the user interface is simple and whatever algorithms they are using to predict the music selection ACTUALLY WORK! I can't recall the names, but when internet radio first came out, I was soooo frustrated with how poorly they actually functioned. Pandora is cool, though--works great, and the music selection is usually pretty accurate when choosing "like artists."
If not for Pandora, I never would have found Amon Amarth! LOL, I love those guys (to an extent)!