You're trying to learn the wordsmith craft, and if you can't fool a stupid computer program, you probably aren't good enough. Eventually, you won't need the program. Then for a while you'll write by the rules, and what you write will be correct, but not as interesting as it might be. The Corel suite competes very well with Microsoft Office. They're both good enough for professional work, meaning that if you use Corel and Grammatik as learning tools, you'll be learning on a system you can use when you hit pay dirt.
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.