Hello,
I was wondering if someone can recommend a good Sub in the $500.00 price range. I'm looking at 65% movies and 35% music. I have a 5.1 set up with B&W 600 series bookshelfs all the way around. I have Pergo floors so I'm not sure if that makes a difference with a forward or downward firing sub. Room is about 15x20.

Looking at SVS maybe or HSU?

PB-NSD10 looks to fit the bill, but are there any better "bang for the buck" subs? I'm sure it will be a huge improvement over my Polk PSW303.

The ED A3-300 seems to be the popular choice in your price range. It's an excellent performer and will fit the bill in your 15 X 20 room.

http://www.edesignaudio.com/product_info.php?cPath=2_41&products_id=102

The SVS PB10 NSD is an excellent performer as well. The HSU VTF2 MK3 is another option but shipping will put it a little out of your price range at $550.

I would suggest taking a look at JBL's L8400. A quick search on this forum will show you that in the Bang-for-the-buck category, folks are quite pleased. I am going to grabbing this weekend. BTW, Check good Ol' Ebay...