Home audio & video forum: Is it ok to lay speaker on its side?

I just purchased my first surround sound speaker system (Onkyo SKS-HT510 based upon CNET's reviews) and am installing it in my living room...a very small living room. On the back wall of the living room I have an entertainment center with the TV and my stereo system. My center speaker is above the TV. The problem is where do I put the Front Left and Front Right speakers. I have bookcases Just to the right and left of the entertainment center. There is no additional room beyond the bookcases. So I have two choices for front speaker locations. First, I can put the speakers in the bookcases. But, since the speakers are 17" tall, I would need to turn them so that they sit on their side instead of their base. Or, I can make speaker stands and sit them in front of the bookcase (not really what I wanted to do since that would block the bottom 3 shelfs of the book case). My question is: Is it ok to sit the front speakers on their side or would that affect the sound distribution pattern and hurt the sound quality?