Ipoker is one of the biggest pokernetworks now(top 6), with many individual poker rooms connected to this network.
If you take the name i poker now, it means you being a copycat/squatter(by bad intention or like you say by not having any idea about poker/domains) and you may want to look into the fact whether ipoker has trademarks on any names with ipoker in it.
I can understand if you would want to take advantage of some other company having build up this name, but you should at least know this when the first google result for "ipoker" leads to this name/result and any internet player knows the name.
Basicly ipoker series would stand for a tournament organized by the network ipoker(like an online tournament week) and I could see how they would not like you using this domain in a silly way. Whether they protected it properly? Or may want to buy it from you after you register it?
I have no sympathy for this or any other poker company and do not think that many of them go aggressively after TM issues by the way, but better safe than sorry.