We live in a part of the country where we can't have basements, and I felt I'd lost a third of my house when we moved here. There are a couple of things to consider. One is that like you, I have my computer in the sewing room and the dust/lint generated by sewing activity is bad for the computer. The other is that if there is radon in your area, the basement should be tested for that before you set up something that will make you spend a lot of time down there. Otherwise, if you can get a comfortable, well lit arrangement in the basement, why not?