Disk space is cheap. Learn to use it all, which means installing it all. If that requires you to get a new hard drive or an Iomega Zip removable drive, so be it. Incidentally, Corel Office Professional 7 works just fine off a parallel-port Zip drive. You can keep your million words on a Zip cartridge, and chances are they'll still be readable years from now.
Most writers manage to rewrite and sell their early material.
In the trade, it's known as selling your trunk. Put them in a room with no telephone, be sure there's neither modem nor games on the machine, and spend several hours a day seated in front of the screen. They certainly work, and since my neat Nimantics Orion 6X laptop has a mushpad, I don't have much choice about getting used to it. The main advantage to mice is that they seem natural, but surely that's a f unction of being used to them. If you've never used anything but a mushpad, it would probably seem natural as well.