Halcyon,
I'll add my two pennies worth as I've just been specing up a new system from ebuyer.
Personally I'm sticking with AMD - had an XP1600+ for two years and will prob go A64 - much better value than Intel.
Are you going to re-use your old case or did you just leave it out of your Doc? I'll be going for the Antec Sonata - designed for quiet computing with 120mm fan and variable fan speed according to case temp.
Why no DVD-RW? You can get a decent DVD-RW for only £30 more than your CD-RW and still write your MP3 CD's. I would also go for a second optical drive (DVD-ROM) so I can copy direct from CD to CD and for the extra ten quid I would still put a floppy drive in (good for recovering dead OS's!).
I could be wrong

but I think you need 'Orignal Matched' DDR to use dual channel mode.
Finally, unless you are a confident PC builder, I would recommend going to a reputable local PC shop (ie not PCWorld

) to get them to assemble the new beast - mine quoted £50, much better than several hours of frustration !