1. Multi-tasking.

We know that this is a slight of hand trick in the OS so to get better tasking we either change the OS or get more CORES. Quad Core machines are now in your price range. Do that!

2. Download speed.

My NETBOOK downloads just as fast as my fastest machine so that's not a machine issue. For this you get a great internet connection.

You didn't supply a country but here you can find machines galore that are quad core and game capable.
Bob