Are you sure its because of the specs? I've had some pretty bad and old computers in my life... and none of them have lagged on videos because of the specs alone. Usually some other problem as well. As for no CD slot, you can buy an external CD drive and plug it into your machine. There almost kind of nicer than internal ones.
@Belldandy: If you are going to end up paying any amounts like 14 hundred, them I am begging you to build your own. The machine you could build for that price would be a thing of beauty, especially compared to the ones you could buy pre-built. Not to mention, this would make it really easy to set up nifty things like three monitors or a neat-o light-up fan system. You know, whatever floats your boat. It really is not that difficult at all, and there are many guides online as to how to do this. Other than that, there are certain websites(I'm pretty sure someone already provided one) that build the computer for you, you just select the parts that you want. It's a little more expensive this way, but still far superior than buying pre-built machines.