I currently have a Nikon D40 with the kit lens and the 55-200mm 1:4-5.6G ED VR. I want to get into wildlife photography. My question is, do you think I should get the 300mm f/4 AF-S or another nikon lens around that price change? Or should I make the switch to Canon? About 50/50 of my shots will be taken in low light, the other half good lighting. Looking for a good, fast, accurate focusing camera and lens combo that wont kill the wallet, and will have really good low light capabilities as well. Any info would be appreciated, thanks