[roostafish]

There's a list of differences that I could go through, but I'll leave it to someone else who will get the facts straight better than I will.

My opinion, bottom line is if you're looking to buy one. Get one that's in the best shape you can, and if you can find one with Ohlins front and rear, that's a good find.

Performance wise, they're all great. I hopped off of my '01 on my friends brand new '07 a couple of weeks ago, and felt right at home. No significant difference in performance that I could tell. Handling is great on both, with perhaps a lighter feel to the '07, maybe a different steering angle, I don't know.
'01-'06 are nearly identical. Perhaps a change in seat/tanks somewhere in there. All the plastic interchanges between those years.