Hi again. 2400+'s native clock speed is about 2GHz. It should be 133MHz x 15. Choose 15.
When in doubt, leave default BIOS settings alone.
Graphic Aperture size - This is the the amount of maximum system RAM (from your 1GB of memory) to be given to the display card if needed. The amount is not locked to the card, so that if card doesn't need it, the memory is still available for system use. If set too high, and card does need and use it, means less memory for system and other applications. With 1GB memory, this should not happen. However, 64MB for AGP Aperture is fairly standard. You have 128MB already on the display card and that's quite good. Quite often display cards with 256MB on most games show little advantage over 128MB cards. No need to change. If you want, you can test a higher setting and run the most memory intensive game you play and see if it makes any difference. But I still wouldn't set it higher than 128MB. If you run into problems, set it back to 64MB.
AGP frequency - this is the AGP bus, which ought to be 66MHz. You won't need to adjust it unless you are overclocking your FSB and want to manually adjust the AGP bus to achieve stability. Leave it at Auto.
AGP 8x - shouldn't matter enabled or not as your card is 4x.
Primary VGA BIOS - Doesn't really matter as you only have an AGP card. But follow the manual's suggestion anyway.