John,
It really depends on what you plan on doing with the car (i.e track days) and what sort of budget you have.
The newer 4 pots are definately a good upgrade for occasional track time. They will require 16" wheels though, so cost can mount. If you are serious about track days then AP 6 pots are the way to go (these will need bigger wheels again)
For discs and pads, i've heard good things about the DBA discs. I've used tarox and mintex discs with excellent results. Although i have heard of folks having problems with warping of tarox discs under heavy use.
For pads Mintex 1144 will give excellent braking under road conditions and some track use as will the Ferrodo DS' pads. Mintex 1155's are better for track use but don't perform as well when cold. Some folks have complained about squealing with mintex pads, this isn't a problem i've had on any of my cars. I think you need to make sure the caliper faces are properly cleaned and make sure you use the rubber anti squeal shims supplied with the pads.
While doing the above it's probably a good thing to look at brake fluid. I think as standard your car should be running on DOT4 (my 95 WRX is) This is more than adequate for daily driving and occasional track days. So just get some more DOT4 and flush out the old stuff to make sure it's all nice and clean (brake fluid can retain water over time). However if you want to go tracking a lot then going to DOT5.1 is the recognised way to go. This withstands a higher temperature however it does require that you completely clean out all your brakes lines as DOT4 and 5.1 are not to be mixed. DOT 5.1 will also require changing more often than DOT4.
Hope this helps
Ian