Tough call. The SVS is self powered so no problem there... but the Yamaha receivers don't seem to come close to their actual power ratings :
http://www.geocities.com/Area51/Hollow/3401/ratevsac.htm
The room containing the speakers is pretty small so I *think* you'll be OK anyways. Make sure you have preamp outputs on the receiver then worst case you can add a power amp for the mains later if you want to play REALLY loud.
From what I remember the Yamaha amplifier stages are good; they just don't have enough power supply to drive 'em all at the same time, so if you offload a couple of channels to a power amp that gives the other channels a lot more power to play with.
My feeling is that as long as you run the mains in "small" (ie send the lowest frequencies to the sub) you should be OK. The SVS has a 300W amp so it should be able to keep up.
EDIT - welcome aboard, and I second the "nice house !!" comments
