Harry - 6:00 am on Jun 30, 2009 (gmt 0) Take your vacation and stop feeling guilty about allowing yourself to live a bit.
You don't have to justify anything. Any human is allowed vacation time. Just give warning in advance and exact date and take your vacation without hogging off with your work. The point of a vacation is not to work. If client doesn't understand that, then client needs to rethink their own priorities. If the work you do is that critical, why didn't they hire a larger company with back ups and more redundancy?
Take your vacation and stop feeling guilty about allowing yourself to live a bit.