Another important thing about boots is the footbed - most boot manufacturers fit their boots with cheap and nasty footbeds to keep the costs down. It can be well worth replacing them with decent ones - this is advice I've seen given on several forums.
The footbeds in my new Hi-tec boots seem OK (but anything would after the old ones I had in my Scarpa boots, which I should have replaced ages ago!) but eventually I'll probably try some Noene footbeds - this is what the blurb says of them:
"These footbeds are only 2mm thick, and yet are capable of absorbing up to 90 % of the micro-shocks received during heel strike. They can be used under, on top of, or instead of your existing footbeds.
Shock absorbing footbeds can help to releive tendinitis, knee problems and back pain."