It's worth some multiple of the traffic and revenue it gets. It's a mispelling of Partypoker, right? Maybe around 36 months revenue since it's not likely to get taken away from you but the lifespan of new poker traffic is possibly limited.
FYI, Lee;
Online casinos will have the .net and .com of a name. If you notice they always advertise the .net on TV. That's because the .net is a free site with "no real money gambling" which is legal to advertise. The .com would not be legal to advertise, as that's where they do the actual gambling.