This is off topic in regards to the thread subject, but while the attention on photography is here, would any of you happen to be members at SportsShooter.com? I'm in need of a sponsor and can't seem to connect with someone that can sponsor me.
There appears to be a sense of elitism amongst certain photographers, which I don't quite understand. I am all about sharing knowledge and gaining some too. Something as simple as obtaining a sponsorship to this SportsShooter website seems to be something of an impossibility. I guess I have not yet learned the secret handshake or something. Anyways, I have shot all three major US pro sports (NFL/NBA/NHL), been published, had work featured in a gallery, done weddings, yadda yadda....anyone?
I'm in the Nikon camp and currently shoot with a D200 & Sigma APO 70-200mm F2.8 EX DG/HSM. It was $600 less than Nikon's version which has VR (Vibration Reduction, equivalent to Canon's IS technology). I have read much about the benefits of Canon gear (i.e. lower noise & cleaner files at high ISO's) and will definitely someday make the switch in an effort to join the status quo of pro photographers. Nikon gear has done the job for me thus far which is why I have not yet made the justification to switch.
In response to the original question, if you have the additional funds to invest in the IS version of the lens, definitely go that route. I started out as a photography hobby enthusiast thus the choice to purchase the less expensive lens I cited above. I'm thrilled with the sharpness of the images created with their lens.