Okay, using
Planet Prices as a guide, this is what I came up with:
P4 3GHz £157.81
P4C800-E Deluxe £128.90
9800Pro (ATi branded) £135.07
2x 512MB XMS3200 Corsair RAM £204.64
Pioneer DVR-A07 DVD +R/RW -R/RW £95.59
2x Samsung 80GB (8MB Cache) SATA Drives £109.28
XP Pro OEM £98
I looked for the Audigy 2 Platinum but only found one listed and the site said "No Longer Available" for some reason. Are they discontinued?
Anyways, that comes to £929.29 without shipping, but still gives you plenty to spend on the sound-card, case and PSU. The cheapest I've seen Office XP was £209, but that requires buying a selected piece of hardware (CPU, HDD or Mobo).
You could go cheaper on some of the parts I listed of course - I'm just brainstorming - so I don't see why you can't get what you want within your budget, or at most just over it.