I'm going to order my 5Dmk2 this week and I need to replace my two cropped sensor only lenses. For my Sigma 10-20mm I have selected the Canon EF 17-40 f/4 L, but I'm having a little more difficulty finding a good substitute for my Sigma 18-200. This is my walk around lens and I really like the range and versatility it provides. It takes quite good pictures for a low cost lens. [FONT="] So I'm thinking the equivalent range for the full frame camera is 28-300. The only lens I found with this range is the Canon EF 28-300 f/3.5-5.6 L IS, but it is $2300 and is beyond my budget. I am leaning towards the Canon EF 70-300 f/4-5.6 IS, but I'm losing the low end of the range that I have with the 18-200.[/FONT] I'm curious to know if you guys have any suggestions on this, particularly you full frame converts.