The younger Valuev who actually treid to win fights and threw punches, like when he fought Vidoz or Ettienne on his way up could be a competitive opponent for Wlad or any HW for that matter. Not that he would beat the best, but it would be a fight. The current version has no will to win and wouldn't be good enough to be Wlad's sparring partner. Wlad has probably beaten 15 - 20 fighters who would beat this version of Valuev.
Vitali or Vlad would knock Valouev out. Chagaev beat Valouev, won the WBA title, Vlad beat Chagaev in the ring.
Vitali or Vlad would knock Valouev out. Chagaev actually fought Valouev and won fair and square. Haye had to depend on Don King's judges after he signed with him.
Though i think that Wlad would beat Valuev, i think moneymatt has some good points. Haye is someone who is ducking and slipping punches, he makes himself even smaller and therefor harder to catch for a giant like Valuev. What Wlad really is great at, is fighting tall. Against Thompson for example Wlad didn´t look all that impressive, as Thompson himself was a big heavy with a huge reach. Valuev is even bigger and it will be difficult to fight him tall. Wlad has never fought a much taller oppenent, he is not the kind of boxer who is slipping and ducking punches. He still has much better footwork than Valuev though and so i think he can beat Valuev simply by moving a lot, but he may be easier to catch for valuev than Haye was. This is not the sure bet, most of you thinking of.
Haye fought smart, no cheating, he outlanded Valuev in every round. Off course not exciting, but effective. Now he has a much better stand to negotiate with the Klitschkos.