Lots of posters here have mixed pots and pans for different tasks - I've got four or five brands floating around in my cabinets that I can think of off the top of my head. As long as your stuff is in good repair, or has a happily used look, I think it's a non-issue. Your goal as host is to make your guests feel comfortable and enjoy their time with you. Do that and no one will care.
If it's bothering the heck out of you, you can give yourself a great look without highlighting your differing equipment. Consider a drawer for your knives.
http://www.williams-sonoma.com/products/customizable-mahogany-drawer-storage-tray/?pkey=ckitchen-organization|deckitdrw
And there are lots of decent, inexpensive pieces that can give you consistency -- you can pick up a basic white $30 dish set from ikea. Their flatware is dirt cheap too if it runs to your taste. And restaurant supply stores have very good and reasonably priced pots and pans, so another good option if you need consistency in look, but also want some quality.