As one of the HT forum guys who honestly knows squat about levels & lumens, my recommendation is to go for one of the hauppauge cards. They're considered "reference" level, meaning every software & h/w mfr makes sure their stuff works with the hauppauge. Plus they're just stable as heck & reliable.
Re:sound - do you mean 2ch, or surround? If just 2ch, then it can come from your PC's headphone jack. If you want surround, then if you have a digital audio out on your motherboard you're set. If not, then it'd be best to get a sound card with digital out. Doesn't have to be big bucks.
BTW, check out the personal website in my sig if you want to be scared about where this path could lead you. That's 99% of the reason I try not to come here too often - i spend enough $$ automating my house; god forbid I get too much of a carPC bug.