I'm thinking that I am going to switch to Canon. I played around with a 50D, at BestBuy today, and I liked Canon's menu system more then Nikons when compared to the D90.
I'll probably end up ordering a refurb 40D from Adorama.
Don
The 40D is an awesome camera, and there are things that I like about it over the 50D (lower pixel density for one). There will be plenty of Canon and Nikon users to help you along the way, whichever brand you choose.