Recommended Tests

I'm trying to build my own computer from scratch, and I was hoping to get some help on the best parts for what I need. My main use will to be watching anime, and downloading the same. I would like to have something that can multitask like no tomorrow as well, since I have several monitors, it'd be nice being able to run more than 1 big program at once without putting a lag on others. Also, I'm not sure what would effect this, but when I use my tv to watch anime, sometimes theres a lag on the refresh rate, making it very irritating to watch. I guess I need help from the ground up on the right tower to memory to the motherboard, even to how powerful wattage I'll need to support it all.. pretty much the best of everything to those needs. Sorry for the selfishness, but this is the only place I know that knows of such details. Thanks in advance, 

Around 1500 to 2000, would probably be my limit.