Mac Pro 2.66 Ghz, 4 gigs of ram, 1TB storage, Decklink Extreme.
With 23" ACD and LCD TV. and a JVC broadcast monitor for preview.

Mac Pro Quad 3GHz
2GB RAM
4 x 500GB HD
512MB ATI Video Card

30" Apple Display and 22" Apple Display

Final Cut Studio 2
Photoshop CS3
Aperture
Many Many More.

XH-A1
HV20
ME66/K6
EW 100 ENG Wirless

I still have an Athlon 2700+, 1.5GB RAM, 730GB HD storage, Radeon 9600XT, but I'm not much of an editor anyways, I'm more into camera and lighting.
I'd give any serious editing in the hands of a friend and she has a dualcore Intel iMac 21" with tons of RAM (2 or even 4 GB??) and FCP Studio. That machine is totally sufficient. It is, according to her, about 4 times faster on rendering than a G5 quad processor.

Btw. if I was more into editing I'd buy a Mac with FCP myself, but I'm not so I stick with Wintel for various reasons.

Dell XPS GEN 3
Dual 10,000 RPM Western Digital Raptors 140 Gb in Raid 0
400 Gb 7,200 RPM Seagate
Intel Pentium 4 Extrem Edition 3.4 Ghz Hyper Threaded
4 Gb PNY DDR2 Ram
ATI X800XT Graphics card
Dual 20in UltraSharp Dell Moniters

Adobe Premiere Pro, After Effects, Audition, Encore Dvd, Photoshop

As well as all my lighting design/ control software

MacBook Pro 15inch glossy
120 gig internal drive
2.16ghz Intel Core 2 Duo
2gig memory
667Mhz DDR2 sdram

625gigs worth of External drives
1-1 dvd duplicator
phillips dvd recorder (purchased pre-macbook)

(main editing machine)
Opteron 165 @2.2ghz (stock cooling)
4GB PC3200 DDR
4x 20" 16:10 LCD
2x 18" 4:3 LCD
1x250GB ops/capture drive
4x250GB RAID5
Radeon x700 PCIe
FX5200 PCI
FX5500 PCI
Shuttle v2
running Vista64

(secondary editing machine = transcoding node)
P4 2.4a @3.0 (stock cooling)
2GB PC3200 DDR
2x 18" 4:3 LCD
1x 200GB ops/transcoding
1x 500GB general storage
2x 250GB RAID1 archive
old Quadro AGP
running XP32

PC
Quad Quad Core 3 CPU at 6ghz (48cores @ 6ghz = 288ghz)
2GB RAM per CPU for 32GB RAM
nVidia OctoMax 8 head video card running 8 x 22" Acer monitors (4x2)
1 TB system hyper hard drive
20 TB RAID 21 media hard drives
Omnimax digital sound card run through Carver amps.
Honda 40 HP genset providing power.
Running MS-DOS 5.0

L4m3r! Everyone knows you can break 7ghz on a liquid nitro'd Core 2 Quadro