It all depends on How seriously you want to play? Any laptop would do if you only wanted to play one game at a time, But if you need to multi-table I would recommend getting a decent tower system with 2 or 3 monitors I managed fine on my old tower system to play 4 games at once but found it would struggle with more than 4 tables open, But I am not that serious anymore, and prefer to play at my own pace playing one game at a time,
Poker is just a hobby for me and I use it to relax and a little enjoyment. Winning or losing really does not matter that much, It is all about how I play and beating other players, the money I win only helps to pay for my losing days and bad beats I sometimes suffer from. But hey! that's Poker!
When the fun Stops, STOP!