Well, it's really difficult to say. Given that your primary concern is the looks of the base unit it's all rather too subjective for most of us to comment on isn't it? Unless we like the same design as you then we'll officially be talking nonsence won't we?
But basically...
Don't even conceive of having less than 1Gb of RAM. Have at least two seperate hard drives. One for the OS and one (much larger) for video.
My current understanding is that for single processor boxes the P4 with HTT are better than AMD. Go for XP Pro rather than Home.
Strictly speaking, a graphics card will make no difference to performance for video editing. However, some special effects programs do use them so I suggest you don't spend a fortune but do get a seperate card rather than built in graphics.
Oh and make sure you get a firewire port.
So anything off the shelf meeting most of this will get you going.
But also you must remember to budget for s/w as well. This might be, for example, Premiere Elements (about £50) or it might be Premiere Pro (over £400). I just quote these as examples, not recommendations. My point is not to forget the s/w as you won't edit much video without it.