It's quite difficult to recommend an off the shelf windows based system biased towards video editing, Matt. They tend to be compromised by all the other things they have to do to appeal to the buying public. Building from scratch is the best solution for this task. It's like your Tiger against a quick, good handling saloon car. It still might be fun around a track but it suffers from needing power steering, soft suspension, air con, etc. Stuff you don't need or want on a track day but vital for the showroom. Your Tiger only has exactly what it needs to stay flat on corners and exploit it's power to weight ratio. Discomfort isn't a concern. I always point new image manipulators towards gaming PCs as they are the closest thing to a graphics biased machine you can buy off the shelf.
I guess my statement was rather fleeting and generalist!, I used to spec and build PCs but in the day ( when MMX chips first came out!) but switched to an IMac 6/7 odd years ago and never looked back. I don’t do games on it as have an Xbox, my main activities are on it are music, photo and film processing and a little surfing. It suits my needs very well, have zero problems in that time. My only need to upgrade is to process HD video, will I get another Mac most probably.
Some great info there chaps and many thanks. Looking into the gear Barstewardsquad suggested to find out a little more
Sorry not any help on the machine choices but I have a quick question, why does everyone say that macs don't crash? They do but due to the sandbox nature of the O/S if a program crashes it just shuts down and clears the memory for the affected program! I have had iMac book programs crash (everything from photoshop to finder) quite frequently on me and don't get me started on ipad/iPhone stuff! The difference is when a windows program crashes it is not sandboxed into its own area of memory and windows can't just clear the affected program from memory so tends to lock up as its waiting on the affected program to do something but never does!