what doesn't linux do that windows does?

[grizzly7]

many people say linux is easy, does everything windows does, faster boot up etc etc, and, considering the question i'm asking maybe the differences are not relevant to my limited knowledge and requirements, but what specifically won't linux do, or, why do i need windows?

we're hopng to travel for several years in our mog, so it can be wrapped up in a duvet for protection, but loooong battery life and 12volt charging are needed.
i have a dslr, i like playing on photoshop with those pics. copying to disc is needed, but can be an external drive no probs.
i need to learn autocad, but those are only 2d drawings and quite small memory wise.
both these are much nicer with a bigger screen obviously.
we'll have a little garmin gps, which will need new maps downloading onto it infrequently i would think, and i have the world base map, so mapsource is required.
the website software is websitex5 which says it needs windows 98, me, 2000, xp or vista, with a 400mhz processor and 128mb ram. the plan is to add to the website, words and pics, while pootling offline, copy to a pendrive and upload each chunk as and when possible. she who will be obeyed has put a lot of effort into the site, and doesnt really want to start again if having an ssd means linux means different software!
will we be loving a 10" eee (keyboard size is fine for us), or throwing it out of the window and wishing we had a slightly bigger windows laptop??

any advice gratefully received!

incidentally, we bought a 400gb pc with lovely screen, thinking i could envelop the harddrive in a dust proof foam and bury it under some furniture, connecting stuff to it as required wirelessly, so it would stay lovely and clean and reliable??. unfortunately, a pure sine wave inverter to run it will cost more than it did, with another inverter for the screen??? which i didnt know at the time B****X!