Markphd.....great post.
In a perfect world we would all have same brand center speakers and even same model but its not a perfect world and there are space, money, wife and others issues that get in the way..........Mark is dead on and dont be afraid to get what you can, if you are careful it wil work great.
Now back to something useful for you, the Vandersteen VC5 is a FANTASTIC speaker (my dad owns one) and while the other Vandersteen center offerings are good the 5 is very good.