Boot issues with using two PCI Host adapters

I want to add a SATA drive to my rig, and I want to know what issues I might have with designating a boot drive.

My rig is old, and I need to replace it, but I can't afford to right now.

Asus A7N8X (nForce 2)
AMD Athlon Thoroughbred (OCed from 1733 to 2167)
1 GB RAM, Geforce 6800 GT, Audigy 2

Adaptec 29160N SCSI 160 PCI host adapter:
-9 GB SCSI 160 (system & swapfile)
-60 GB SCSI 160 (games and DVD editing)

Onboard IDE channel, primary master:
-320 GB IDE/100 (storage)
Onboard IDE channel, secondary:
-1 DVD-RW and 1 DVD-ROM

I want to move the 320 GB IDE drive to my living room PC, so I can build a raid 1 array (there is already an identicle 320 GB drive in that PC). I still need storage for my main rig, though, so I need another 320GB drive.

Since I'll be building a new, SATA only computer in a year or so, I want to buy a SATA drive to replace the IDE drive. That means buying a PCI based SATA adapter that can coexist with my current Adaptec PCI SCSI adapter. NewEgg has an inexpensive, 1-port SATA PCI adapter that has gotten some good reviews.

Here is the problem: in my mobo BIOS, the only option for boot chain is "SCSI". It doesn't let you identify which adapter... Does anyone think this will work? How will the mobo "pick" a host to go first?

You should be able to move the cards around and make one boot instead of the other that way.

Be aware that you're getting into some real voodoo once you have multiple PCI adapters. I had a problem recently with a PCI IDE card and a SCSI adapter. I could install both of them, and the system would just hang and not attempt to boot. With just one or the other, it boots fine. Swapping around the order of the cards eventually got it working.
If you're buying new drives though, why even keep the SCSI setup? It's 70gb of hassle, and will be outperformed by a nice new SATA drive for desktop use. My advice would be to ditch the SCSI and get a 400gb drive.

Yeah, I hear you, the SCSI is nearing the end of its useful life. However, I doubt that SATA is that much faster, specially considering the bottle-neck of the PCI bus.

The 60 GB SCSI drive is a 10,000 RPM model, and it screams. I use it for doing my DVD editing, which is very disk intensive. Plus I like the reliability of having a small drive for your OS, as I make an updated Acronis disk image every month. Last month it really saved my bacon: I got a nasty peice of spyware I couldn't get rid of, so I just wrote an image over my system disk. I was back up and running as normal in about 30 minutes.

If your SCSI card allows you to turn off the BIOS or disable it as a bootable device, that would be your best option.

If you're not wanting to boot from the SATA card, then you're pretty much stuck with putting the SATA card in a lower slot than the SCSI card so that it's ROM isn't loaded before the SCSI card's.