Folks ....... Anyone help with a few ideas on getting a new spec PC ??

My needs :

Spend - GBP 1000
I do a reasonable amount of video editing, but here was what I was thinking - not entirely sure if this can work though :
External hard drive to store films.
A split drive : Split drive to run XP Pro in one and Vista in the other.
If not an option, or more thought given to it ... A split drive both on XP Pro.
One where I can download music, various applications - some from questionable resources and the like. Have it in my head that since some of these programmes come occasionally come with some uninviting additions, should I start to develop unstable blue screens and the like, I can then rely on the other half of the drive ... or does it not work like that?

Also, was considering Quadcores, but aware this will push the budget up, so was wondering if there was an alternative, or a motherboard where an upgrade would be possible at a later stage?

When I considered upgrading last year, I was considering Evesham and went for a pretty basic system but upgraded elements of it.

Anyone know of any other reliable ' self build ' companies??

One thing the PC will not be used for is games.

Any advice is warmly welcome !!!

Cheers