"Ultimate" ultimately depends upon your budget. When considering high
performance, system cooling and power are where many try to save money
and that doesn't work. A case that is capable of filtering dust and
moving a lot air (or liquid cooling) and a power supply that will
provide consistent reliable power will eliminate a lot of problems over
time.
Windows Vista has a performance rating system that gives a simple
benchmark of a computer's capability, and a recommended rating to run
specific programs. On the system I just built, the processor (an AMD AM2
5200+) is the "weak" link ( a rating of 5.1 of a possible 5.9). All
other components maxed out. Dual Raptors in RAID 0, 4 GB PC800 RAM,
640MB 8800 GTS OC Video. The power supply is rated at 600W, with 3 12V
rails @ 18A per with a total rating of 50A.
Obviously, the system I built could be improved upon- especially the
processor and the video card (the GTX version w/more video memory).
There is other hardware in the system using power and memory, but not
important to the question you asked. The whole thing cost just under
$2000. It will not play all games on the market now, because I'm using
64 bit Vista, so there are compatibility issues with some games. Newer
games however, run flawlessly- I've got 50+ hours on BIOSHOCK with all
the DirectX 10 graphics maxed out and haven't had a single problem- runs
smooth, looks great.
Whatever components you decide to use, make sure you build in
reliability to go along with performance- you won't be happy traveling
at light speed into a BSOD because of overheating or inadequate power.
Good luck-
