In reply to Summithunter:
When you say high altitude what height you talking about? Spantics are about the best you can get up to 7500m in my opinion, combined with good socks and proper acclimatization you shouldn't need anything else! Never tried or spoken to people who have used electric socks etc, so cannot really comment, just wonder how much extra weight that would be in terms of battery's and the kit, remember at altitude every gram makes a difference. A lot of people get cold simply because they run out of energy humping around the likes of a huge SLR with spare battery's etc, half their summit kit must be electronics. Best thing to keep you warm after proper acclimatization is a good breakfast and a flask of tea, at least they get lighter as the day goes on!