If you don't know, the reason that scores can't normally go below a 3 in character creation (other than racial penalties and suchlike, perhaps?) is that in normal dungeons and dragons stats are generated by rolling 3 6 sided dice and adding them up. There are several variants to that system to ensure you don't get terrible scores, especially in your key stats, but they mostly revolve around that mechanic. In fact, BG uses a variant on the system itself: it rolls 3 dice for all 6 stats, rerolling any that are below minimum requirements for your class, but then lets you reassign the points as you wish. That's my understanding, anyway.
Geoguy's table only shows strength, but it appears that if you replace 'str' with 'dex', 'int', etc in the link it'll take you to the other tables.
Yea sorry I wasn't fully reading the original post apparently.
Are a few more examples (they aren't necessarily full tables for all the effects that different ability scores give).