Well you won the challenge and got a copy of ViewingDale didn't you so there should be few limits as to how big you will be able to map with that. I have a 160,000 pixel square map running (ok so its slow) but it can do it. That burns multiple 10's of Gig HDD space but it does not map quite the same way as PS or a bitmap editor so you may find that you will have to adjust your usual techniques. You will have to tile a really big image but the app will take the chore out of the composite of the tiles. What DPI are you aiming for - what final pixel size image ? 46inches at 300 dpi is only 14K pix which is no big deal at all. Because your 64bit you have higher max sizes than 32bit too. 6Gb is more than me not that it will make much difference anyway.