Well, let me try to convince you
1. Do you ever watch poker videos? Inside PokerManager you will find the worlds biggest archive (do a search for "poker" and you will see there are close to 50 000 videos of various length)
2. Do you ever play a online poker tournament? Inside PokerManager you will find a tournamentlisting from almost every network available. I you are happy with playing just 1-2 clients, thats fine...but if you are like a lot of others having trouble finding just the right tournaments at just the time you want to play - well there you go...pop inside PokerManager and you will 99% certain find one within minutes
3. Do you ever wonder what your odds are/were? Inside PokerManager you will find a brilliant odds calculator. In addition you have an advisor that shows you on-the-fly advice (for those of us that not allways know their odds *blush* )
4. Do you ever read any poker articles? Well, inside PokerManager you will find the latest news and articles from the leading pokermagazine
5. Do you ever chat with friends on skype/aim/msn, but find it annoying when x-girlfriends wants to chat with you JUST when you for once ( ehh ) are playing poker? Inside PokerManager you will find a poker IM, and can add your pokerfriends there.
6. Do you ever miss the start of a tournament you really wanted to play (a satelite or something)? Well, inside PokerManager you can right click any tournament, add to calendar and voila - you will be reminded 60,30,15 and/or 5 minutes before it starts. (even by SMS in the next version)
7. Do you ever visit any forums/communities? Err...i guess you do
(...and loooads more)
If you can't find 1 reason to use PokerManager, well maybe it's just not for you...hopefully you will give it a go though. We will do our best in constant developing it, and sooner or later we will have something that YOU also will find useful

Oh btw..it's free, so you are not risking any hard earned € giving it a go