According to the SRD 3.5, It is only "extra damage dice" (sneak attack, flaming, etc) which are not multiplied during the calculation of a critical hit. Damage not expressed as dice (strength, weapon bonus, specialization, etc) should be multiplied.
http://www.d20srd.org/srd/combat/action ... iticalHits
My 18 str knight who is wielding a falchion should score 4d4 + 12 on a successful critical, not 4d4 + 6.
Other than that, really enjoying the game.