OT Sam_O,
How to spend other people's money and have a good time doing it. I personally prefer AMD just so Intel will have a reason to keep prices low. That being said, lets build an out there on the ragged edge machine.
From Newegg.com
Intel 2.8ghz socket 478 CPU model BX80532PG2800D 800 speed FSB retail box with heatsink and fan....$268.00
Asus P4C800 Deluxe motherboard with Intel 875P chipset .............................$181.99
Thermaltake W0013 550w power supply...$70
Asus V9520 Geforce FX5200 AGP8X video card with dual VGA out ................................$89.99
From MS4ME.com
Two 512mb Samsung PC 3200 ECC REQUIRED DDR 400 Speed ram sticks .......................$108.00 each total...$216.00
Total budget....$825.98
Keep your case. Keep your disk drives and all externals. Trash your old power supply. The new motherboard and powersupply will have automatic fan speed controls which is a nice touch.
This machine guaranteed to score 100% (faster than 100% of all machines tested) at PCpitstop.com in comparison test.
If you decide to go with the duplication of my personal AMD machine, you will only be faster than 99% of the machines out there but you will save about $250.
Good luck,
BT