Yeah, I'd rather have a 300 f4 for the price, but the deal I got was too good to pass up (local). It will make a good combo for when my wife is second shooter at sporting events. It's a very solid telephoto and much lighter than the 2.8 IS version. I'll probably be looking to swap it out for the 300 f4 eventually though....
I still have one of my 40D's, but I sold the other one a while ago. I got my asking price ($650) on Craigslist locally. I got lots of interest, but had quite a few people back out until I got one person who e-mailed it, and met me with cash an hour later!