theres loads of people who dont though most only spend around 700 on a base unit.
1600 every 6 years would be better turned into 800 every 3 years
to some 100 quid does matter but i guess it depends on how much of your comp your upgrading a lot of us buy a really nice expensive case to keep for a very long time then only really upgrade the mobo+cpu+ram+gfx card every other year and new hdd/cd/monitor as needed
I have to agree with the distribution of cash over time, been too long since I upgraded! I'm also doing just what you say, buying an 800D which should last me some time I hope Subject to reviews I'm leaning more towards the i7 just for longevity as it will have more headroom I think before the CPU becomes a bottleneck. If Bulldozer had been compatible with AM3 I would be more inclined to stay loyal to AMD.