quick receiver/speaker setup question

[tbizzle]

Well I'm setting up my speaker system again and I was wondering what I should set my speakers to in terms of large or small. I was waiting to hook up my CS2 until I get my new Monitor 70's, but I was advised to hook it up anyways so I just wired it up and moved a few things around. Here's what I'm working with:

Fronts: Polk R50's
Center: Polk CS2
Sub: Polk PSW10

Receiver: Onkyo 506

Q's:

Should I set my fronts and center to Large since I don't have a super powerful sub, or should I let me sub handle the bass and set the others to Small?

Also, what should my crossover be set to? The manual says speakers 6 1/2 - 8 in should be 80hz, and 5 1/4 to 6 1/2 set to 100hz. I'm guessing mine should be set to 100

Any help is appreciated, thanks