STEP AWAY FROM YOUR COMPUTER... Don't order THAT lens. The next version, with OS, is considerably better. I owned the earlier version, wasn't happy. Bought the later version (on Sigma.com, as a refurb), and liked it enough to sell off my Canon 24-105L. Every bit as good optically, even if a stop slower.
The newer 17-70 does a NICE all-around, including it's "macro" feature. It fits in beautifully with my 10-20 and 70-200L as a traveling kit.