hi, i m planing to play a melee/bow (depends on a situation) rogue but i was wondering about picking either sword or dagger skill, is there a big difference there ? i have heard that daggers are largly underpowered in book one and i simply do not fancy to roll over when i realized something is wrong with my build :)

If you're playing a ranged rogue with occasional melee action, I would go with short bladed, unless your rogue has the strength to deal with the extra inventory weight of swords. It also depends on how you intend to use your rogue, melee-wise. If you need maximum damage at all times then consider swords, otherwise stick with short bladed hit-and-run. The bottom line is that full rogues are not meant as front line damage dealers.

So you are saying that it is not a wise idea to go hybrid in this case? i was planing to go 50/50 melee/range.

No, that's not what I'm saying. What I am saying is that your rogue should have a clearly defined role -- he/she should be a master of that role, not a jack of all trades. Your rogue can fit both roles, but should be a specialist in one (he/she is NOT a Fighter/Rogue).

I always go with 2 concentration 1 strength. That way I get a little health and damage for swords, but mostly I get more damage with concentration for bow. You could also go 3 concentration per level and use the excess to hit to hit enemies in melee when running out of arrows.
Rogues are meant to be ranged most of the time and skewer enemies with a light jab when melee is only choice. For skills I would go 2 bows and 1 whatever melee weapon you use.