Im going digital. The package im looking at is the Canon 20 with a2GB compactflash card form B&H. My question is the lens im looking at is 70-300mm f/4.5-5.6 IS USM. my main goal is soccer photos. Is this lens "fast" enough? and is the IS needed for sports. I have a EF 35-135 USM from my 35mm EOS rebel. Any help or suggestions welcome.