I'm looking at the 18-200mm class lenses for my D40. The Nikkor is just too expensive, so it's down to the Tamron and Sigma lenses. The Tamron is only $230 after rebate, but is probably the "worst" of the three - looking at a side by side it's pretty damn fuzzy compared to even the Sigma. The Sigma without optical stabilization is about $290 and is about as sharp as the Nikkor in the center and just a little fuzzier around the edges. And 1/3stop slower at the long end. I'm fine with all that for a $300-400 savings. The Sigma with OS is about $70 more that the Sigma without, and is substantially heavier. I guess the question is whether the Sigma is worth the extra $60 and if the OS is worth another $70 and half a pound on top of that? I'm inclined to go for the "best" lens (Sigma with OS) but the idea of $130 in my pocket and half a pound not in my bag (or on the end of my light camera) is pretty appealing. Any advice?