What a coincidence, I have my number since 2008 too!
I looked up on Google the Italian mobile networks, just out of curiosity. Wikipedia says there are only 4, even if the page has last been updated 2 days ago!
Wikipedia says there are: Wind, Vodafone, 3, Tim. That's not accurate information, there's Fastweb too and they even have nice offers (lots of minutes within national networks, lots of SMS' as well).
Well, to simply answer the question, I'm still on the Vodafone network. I'm thinking of changing it though, maybe with Wind, not sure yet.