There are many cords that will make a big improvement over ANY stock cord. One of the better places to start are the Chris VenHaus designs. I have a few of them around still, but mostly on the computer and stuff like that. Stock powercords are not good, anything will be an improvement, but there is no need to buy $2000 power cords for $500 equipment.
There are a lot of DIY designs that can be very effective too, if you don't mind doing a little work. Again Chris Venhaus can help, as I think he still sells kits. I could be wrong about that, but if he doesn't there are others here who do sell them.
I would consider an after market PC a good investment. If you're not sure, but a used one, if it doesn't satisfy you, resell it.