Good way to configure multiple drives.

Let's say you have one 18GB SCSI, two 100GB IDEs and one 60 GB IDE.

You're also putting in a CD burner and a DVDROM.

Your mobo has 2 IDE channels. According to the manual;
"It is recommended that non-UltraDMA/100 devices be connected to the secondary IDE controller."
I don't know what the reasoning for this is since the manual also says that both channels are UltraDMA/100.

All the HDs are ATA100.

The mobo won't take SCSI directly so you have a SCSI expansion card for the 18GB SCSI and an IDE controller expansion card for 2 additional IDE channels (bringing your total IDE channels, mobo and card, to 4).

You use the comp for web design, games and high resolution image processing.

Without going RAID, which drives would you put on which channels?
How would you organize all your data (OS, swap, apps, data, scratch, etc.) among the drives?

The motherboard is Asus by the way, so if anybody has some idea why it says that in the manual please let me know. It's a P4 series.

This IS for YOUR computer, isn't it? I wonder why you kept using 'you' instead of 'I' in the original post. It's like when I hear people ask and begin with: "I have a friend who has this problem....". It's so obvious that they are asking for themselves. Anyways, for your problem (my problem), I would forget about the scsi drive unless you already have the scsi card. No point buying a scsi card for 18G of space when you already have 200+. Even if the scsi drive is out, you still have 5 ide devices. If you really need all of them, you must get a IDE/RAID IDE controller card. RAID or no RAID is up to you. For the imaging applications you listed, stripe RAID the 2 100G would be helpful. Understand the consequence tho. When one drive in stripe goes bad, you risk losing everything in the array. If safety is more important than speed, mirror RAID the 2 100G for work and use the 60G for fun. Keep all harddrives on the controller card because you can then put both rom drives as masters on the onboard ide channels (good for cd copy with on-the-fly mode). I think the reason why Asus recommend you not to put ata100 drives on secondary is because the board comes with one ata66/100 and one ata33 cable. Using ata100 drives with ata33 cable is certainly not desirable. If you are to put scsi card and ide card, make sure you research enough for conflict issue between the 2.