I have an iPhone 4S and had the same issue. I had 4GB (!) of photos and videos on my phone (didn't realise until I wanted to do the update) so plugged it into my PC, opened "My Computer", half sized the screen, opened "My Pictures", again half screened it, so I had both screens side by side, then in "My Computer" double clicked on my iphone icon, opened up the pictures folder, dragged and dropped its contents into "My Pictures" and when completed clicked on "My iphone" again and ensured all the pics/videos were still highlighted and then pressed delete. Once they were gone I had enough space to download the update. Hope I've not stated the obvious above and it makes sense
Ok, I have an iPhone 5 and want to update to ios7.
I don't have enough space to do so though.
My phone is mostly taken up with all my music and photos.
So do I sync it with iTunes, remove from PC, plug into wall charger, delete chunks of music / photos to free up space, then download ios7. Finally I plug iPhone into PC and (somehow) get all my now deleted music and photos back?
Sorry for being dim but I don't want to lose what I have.