Strength is a very important statistic for everyone. You can never have enough strength I say (if you have extra trains, that is. But who has extra trains?).

Strength starts off by giving bonuses (or penalties) to your damage roll. Damage roll (shortscripted to DR) essentially adds damage to your base attacks. This is obviously important to every warrior sort in the game, in order to maximize those extra attacks you get.

Secondly, strength is the only thing that has a role in your max weight figures as you level. Simply put, the more strength you have, the more you can carry. Your max weight goes up naturally as you level, but it will always be directly multiplied by your strength. Note that this is important for any would be house raider, because stones of power are very heavy, and it's always a dry feeling to have to raid a house again just because you couldn't carry a stone of power.

Additionally, this is also an important thing to consider for void scholars; spell components (particularly body parts) are somewhat heavy and begin to pile up after awhile. Earth scholars also benefit from this (they already get a giant strength spell) in that they can wear more shaped armor and still have breathing space to carry additional items.

Another important dependency on strength is your capacity to wield heavier weapons. More strength means heavier weapons, but this isn't so important in itself. What IS important is its relationship with dual wielding. Your secondary weapon in dual wield is limited by the weight of your primary weapon. Thus, the heavier the primary weapon, the more slack you have in choosing a secondary weapon. The more strength you have, the heavier the primary weapon you can wield then. Are you starting to see the chain of effects here?

Because of its direct relationship with weapon weights, strength is a popular attribute to attack (Attribute attacks are when someone drains a particular spell via skills and spells). If you are wielding a heavy weapon, and your strength gets lowered below the minimum wield value, then you drop the weapon (except with noremove weapons, then you simply can't attack). You drop the weapon, you drop your guard, and it usually results in death to people who aren't prepared.

In conclusion, strength is useful for everyone. There are a few skills out there that have a direct save based on strength (ex: breaking free, etc.) so it's usually in your best interest to get a decent strength stat, even if you have to use +str items to accomplish such.

Intelligence

Intelligence is a useful statistic, but not necessarily weighted as being important. The direct effect of intelligence is that its one of the two stats that has a role ni your mana gains. This is important to scholars and templars, for obvious reasons. There are a lot of +int items in the game that are accessible at a low level, and most often people simply switch on +int gear when leveling in order to maximize their mana gain chances.

Your intelligence stat also has an effect on your usage-percentage gains. Guilds will only let you practice a stat up to 75%, after that you must gain percentage points by using the spell or skill in the field. With every usage, you stand a very small chance (which I believe, differ from skill to skill) to getting better (you'll be told when you do). The chances of that increase go up (and perhaps, down) depending on your intelligence. This is a player call, as far as I'm concerned. All skills and spells will reach 100% eventually, it's up to you if you want to speed it up or not.

At this point, it should be painfully obvious that intelligence doesn't actually bear a lot of importance in terms of mechanics, and how you allocate your trains. Intelligence can be handled completely via equipment, if you so choose. But please, don't roleplay an "intelligent" character with an intelligence of 12. That's just bad form, and immortals WILL notice it.