You never got into using auto focus SLR cameras, so that makes a difference. Any digital SLR will be a big change, even if you only use the camera in manual shooting modes.
I suspect that based on the lenses you own now, and the fact that you like your lenses, that switching systems may not be the best idea. Even a crop sensor camera will be a big change, because the focal lengths that you are used to will not appear the same. All lenses will have a 1.5x crop (35mm is more like 50mm for example). That crop factor is even greater on 4/3s cameras (2x, 35mm = 65mm) like those from Olympus and Panasonic. The only way to avoid that is a big, expensive and heavy, full frame DSLR, which might not be the best choice unless you don't mind the price tag.
Best advice is to go into a camera shop and ask if you can try out a few of the newer cameras. See which ones you like in terms of size and weight, because all of them, short of the D3000 and D5000, are a lot bigger than the FM series of cameras.