Don't worry about the "watts" because that does not tell how loud a system will be able to get. There are too many variables involved.
That said, here's what I would get with a $450 budget...
- Dayton 5.1 Home Theater Package with 12" Powered Subwoofer
- Pioneer VSX-519V-K 5.1 Home Theater Receiver
- Pioneer DV-420V Upscaling DVD Player with HDMI
You can find these on eBay, Amazon, or Parts Express.