^ lol dat price.
find a sound system with an HDMI pass-through, you'll need it when Hi10P or 10Bit gets too popular and hardware players still doesn't support them.
the purpose of this is for your sound system to receive the audio signal via HDMI connection from your player/HTPC and pass the video to the TV as is without modifying it, so if your player/HTPC sends out 1080P then the TV will receive 1080P. well since most TVs doesn't have built in 5.1/7.1 sound system on them or just sounds horrible... you get the idea.
HTPCs will auto-magically upscale SD sources btw.
but i do have to warn you, any path you'd choose will be expensive, be it buying decent amplifiers + decent speakers and being contended with analog outputs, or going pure digital via decent AVRs.
you can end up with a really solid low end get up for like 850
thats 5.0surround 5.1 for another roughly 100-150
using polk monitor 70s tower speakers in front cs2 center and monitor 40 or w/e in the rear
with a minimum of 200 on your receiver
towers on sale go for 150 each - 300
center on sale is 99 - 100
rears on sale 130 pair - 130
decent receiver - 300
and you have a solid ass sound system that will shit bricks on movies and sound great for music
throw a sub in there for roughly 125
these prices happen at least once a month for speakers on newegg