However, as far as I can tell, most forms of PR that might be implemented would focus on making the number of MPs in government proportional to the vote, which to me is a step in the right direction, but this wouldn't make the actual power proportional to the vote, as we have a system where all the positions of power are generally held by the ruling party.
At the moment it seems unclear what the purpose of an individual vote is. Are you voting for the MP who will represent your views in parlament, the party you want to govern the country or the person you want as prime minister? I would say that the system is setup for the former, but most people use it for the latter. You just have to look at the arguments about whether Brown has been democratically elected to the position of PM to see the level of confusion here, and, yes although he has gained the position fairly under the current system, it seems somewhat undemocratic that a PM should be replaced only by a vote from the ruling party.
I would personally, like to see this changed so that not only were government elected by some form of PR, but that also the leader of the party with the most votes didn't automatically gain the position of prime minister and the power to give all the other positions of power to his/her mates.
Personally, I would prefer to see these positions elected by the whole government from within their numbers, so for example, when Blair stood down rather than having just the labour party vote for the next prime minister, it would have been the whole government and would have excluded any members of the labour party who didn't have a seat.
If the make up of government represented the views of the people, then so would the make up of the cabinet, because they would have been elected by our representatives. It would also help even out the power distribution between the ruling and opposing parties and help clarify that the purpose of the elections is to appoint your representative(s) in government rather than the cabinet.