When you buy a new computer, you just need the box, not everything else. $400 should easily get you the speed you need. And if you go to a good shop, you can just have the necessary components replaced for even less as long as your current box isn't too old.

If you use the sim a lot, it's a good investment. I'm likely going to upgrade next summer, after the heli upgrade is available, the bugs have been worked out of the program and CPU's are just a little faster.