EHM 07 is the best version that was released. I own them all and I enjoy them in this order...
EHM 07 > EHM 04 (First one called NHL Eastside) > EHM 05 > EHM (steam version)
People recommending the new Franchise Hockey Manager but I would disagree, the game is now up to version 7 and is still very rough around the edges and is a very different product to EHM. If you only care about up date NHL game play then sure go buy Franchise hockey 7 otherwise stick with EHM 07 if you have it!