Dell Computer Corp., the leading direct seller of PCs, plans to unveil a machine in the fourth quarter that will connect users to Dell's computer support desk with the touch of a button. Dell officials wouldn't say how much the new machine will cost. The PC, code-named Webster, is part of a larger effort by Dell to automate computer services. The company unveiled a plan called "E-Support--Direct from Dell," by which buyers of all its machines eventually will be able to access automated technical support, making it cheaper and easier to provide. Dell shares rose $2.63 to close at $49 on Nasdaq.