For someone who has to have the best possible system regardless of cost, a pre-overclocked rig may make sense. With the cost of the boutique type machines you can get technical support and warranties that would not be available if you built your own oc machine.
playing around on overdrive's site I managed to put this together if money truly is no object, although you could save $38 and substitute the x2 4800 for fx-57:
System Warranty and Coverage : [Platinum] (3 Year) Parts & Labor Warranty
Case and Color : [Lian-Li] (Custom Painted) (Aluminum) PC-60 (VapoChill Case)
Ultra-Quiet SureCool System and Fan Colors : Fan Lights (Green)
Processor Cooler(s) : [VapoChill] (Refrigeration) (CPU) LightSpeed
Power Supply : [PC Power and Cooling] Turbo-Cool 510 (510 Watt)
Video Adapter : (2) [NVIDIA] GeForce 7800 GTX PCI-E (256 MB) | HyperClocked
Disk Array 1 | Hard Disk Drive(s) : (2) [Western Digital] (74GB) (SATA) (10,000 RPM) Raptor
Disk Array 2 | Hard Disk Drive(s) : (2) [Seagate] (SATA) (400GB) (7200 RPM) NCQ
Processor(s) : [AMD] Athlon 64 FX-57 HyperClocking Pending!
Motherboard : MSI K8N Neo4 Platinum SLI nForce4 PCI Express Motherboard (939)
System Memory (RAM) : 4.0 GB (Custom Modules) (Rated to 550+ MHz) (DDR)
Operating System : [Microsoft] Windows XP (Professional)
CD/DVD Disk Drive 1 : [Plextor] PX-716SA/SW 16X DVD-RW/+RW
CD/DVD Disk Drive 2 : [Sony] 52X CD-RW 16X DVD Reader
CD/DVD Cable Color : Rounded Cable (Steel)
Floppy/Flash Drive 1 : [Mitsumi] (Floppy / Flash Media Reader) (1.44MB) (3.5")
Floppy Disk Drive Cable Color : Rounded Cable (Steel)
Sound Adapter : [Creative Labs] Sound Blaster Audigy4 Pro
Speakers : [Klipsch] (5.1) ProMedia Ultra
System Utilities and Protection 1 : [Symantec] Norton AntiVirus 2004 (Pre-Installed FREE)
Shipping Options : [FedEx] (1-Day) Service (Computer Only)
System Price : $10,920.00