[EvilEdwin]

With dual wielding the best "penalties" you get are -2/-2, but to get that you have to use a light weapon in your off hand (ie one that is smaller then your size, so small or tiny for medium size characters), as well as the two feats. Since rapiers are both medium sized weapons you won't get -2/-2. Can't remember what it is I'll check later.

As for weapons there's quite a good spread across all types. You can check in the tool kit to find out what they all are (but you might consider that cheating!!)

At the moment I've got a Halfling Fighter/Rogue who dual wields a small sword and dagger (or mace if fighting undead). I put weapon focus, weapon specilisation and improved critical in short sword.

When I planned my character out I had a good look at the weapons in the tool set so I knew what I wanted to use. Might be worth doing so you enjoy using your character. But if this is your first time through you might want to wait to do that so it's not spoiled for you.