I would just buy an ultra high end gaming machine...
COOLER MASTER Stacker 830 RC-830-SSN1 Silver Aluminum ATX Full Tower Computer Case - Retail
$259.99
PC Power & Cooling Turbo-Cool 1KW-Quad SLI T1KW-4E EPS12V 1000W Continuous @ 50°C Power Supply 100 - 240V UL/ULC/CE/TUV - Retail
$509.99
ASUS P5N32-SLI SE Deluxe Socket T (LGA 775) NVIDIA nForce4 SLI X16 ATX Intel Motherboard - Retail
$249.99
Intel Core 2 Extreme X6800 Conroe 1066MHz FSB 4M shared L2 Cache LGA 775 Processor - Retail
$1,149.99
OCZ Dual Channel EL Platinum XTC 2048MB PC8000 DDR2 1000MHz Memory (2 x 1024MB)
$451.99
OCZ Dual Channel EL Platinum XTC 2048MB PC8000 DDR2 1000MHz Memory (2 x 1024MB)
$451.99
BFG Tech BFGR79512GTXOCSINE Geforce 7900GTX 512MB 256-bit GDDR3 PCI Express x16 Video Card with SiN Episodes: Emergence - Retail
$475.00
BFG Tech BFGR79512GTXOCSINE Geforce 7900GTX 512MB 256-bit GDDR3 PCI Express x16 Video Card with SiN Episodes: Emergence - Retail
$475.00
Creative Sound Blaster X-Fi Elite 7.1 Channels 24-bit 96KHz PCI Interface Sound Card - Retail
$375.00
Western Digital Raptor WD1500ADFD 150GB 10,000 RPM 16MB Cache Serial ATA150 Hard Drive - OEM
$249.99
Western Digital Raptor WD1500ADFD 150GB 10,000 RPM 16MB Cache Serial ATA150 Hard Drive - OEM
$249.99
Seagate Barracuda 7200.10 ST3750640AS 750GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - OEM
$399.99
Seagate Barracuda 7200.10 ST3750640AS 750GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - OEM
$399.99
PLEXTOR Black 16X DVD+R 8X DVD+RW 10X DVD+R DL 16X DVD-R 6X DVD-RW 16X DVD-ROM 48X CD-R 24X CD-RW 48X CD-ROM 2M Cache SATA DVD Burner With White bezel,AUTOSTRATEGY,PoweRec - Retail
$105.99
PLEXTOR Black 16X DVD+R 8X DVD+RW 10X DVD+R DL 16X DVD-R 6X DVD-RW 16X DVD-ROM 48X CD-R 24X CD-RW 48X CD-ROM 2M Cache SATA DVD Burner With White bezel,AUTOSTRATEGY,PoweRec - Retail
$105.99
Swiftech H20-220 Apex Ultra+
$349.99
Swiftech MCW60-B VGA Water Block (3/8 & 1/2)
$44.60
SAMSUNG 244t-Black Black 24" 6 ms (G to G) Widescreen LCD Monitor 500 cd/m2 1000:1 0.27mm Pixel Pitch - Retail
$856.99
Logitech G5 Laser 931376-0403 2-Tone 6 Buttons 1x Wheel USB Laser Mouse - Retail
$52.45
Logitech G15 2-Tone 104 Normal Keys USB Wired Standard Keyboard - Retail
$68.99
Logitech Z-5500 505 Watts 5.1 Speaker - Retail
$263.99
And that leaves just under 3000$ to mess around with. Hmm, maybe a second monitor? Maybe a big 30" for movies? Hmm probably the most idiotic thing to spend more money on in a system like this but I would do it. I would get TWO Z5500 speaker systems.
That means a second soundcard as well. And thats with the theory that you can run everything in windows and games or whatever through two sources... Then offset each speaker set by 10 degrees. (center speaker is default 0 degrees than have the two centers are 350 degrees and 10 degrees.) I think that would add a neat effect.. It might completely suck. Guess I wont know until I try it. I personally believe this is the best system without going to exotic... such as thermal electric cooling, or raid5, or complicated raid card, or quad sli... wich I personally believe is inferior to two 7900gtx in sli. Ya, it's easy to slap the most expensive parts in a system... but I think this machine is far from that. The only piece I don't know to be the best in it's catagory is the monitor. Best cpu? Memory? Motherboard... only one I can think of that supports SLI and is a premium board, and does conroe. Well... enough dreaming for one day.
EDIT: After re-reading this build a couple times I noticed that maybe 4x 1gb sticks aren't the best until Vista, that could handle the ram. Also I most likely don't have the BEST water cooling system in there... But what I do have is still extreme high performance and simplicity.