The Three-Year Itch

It's been more than three years since I last built myself a PC. It's
that time again.

I'm planning on a P4 3.2 this time, with XP Pro, mostly to run MS
Office apps, Photoshop, music-notation programs, occasional gaming,
home-recording/editing of guitar-playing, and video-editing.

My main question right now is what to use for hard drive(s). In past
machines I've built or upgraded, I simply bought a new IDE drive and
used the previous drive as an internal backup or secondary drive.
Nothing fancy. But now I'm wondering if I want to get into SCSI, SATA,
RAID, or who knows what. Should I plunge into a more involved HDD
subsystem?

For instance, what about having Seagate Cheetah 15k SCSI drive for the
OS and programs, and another 15k Cheetah for whatever else. In the
"old days" it was often recommended to place the OS on one drive and
data on another, giving a nice performance boost -- especially for
digital audio workstations (DAWs) -- but I've never tried it. Does
that advice still apply?

I'm not as concerned about expense as I am about no-hassle reliability
and snappy performance. SATA sounds too new to be really reliable, and
RAID setups sound like a lot of hassle. Am I on the right track in
thinking SCSI, or should I just stick with plain old PATA? If PATA,
are two internal drives better than one (one for OS/progs and the
other for data?)? Is there more security in RAIDing/mirroring two
internal drives, or in backing up to an external hard drive?

Plan A, the simplest, would be to buy a 160GB Barracuda IDE drive for
$80 (CompUSA), use it as the C: drive, and to back up to an external
drive.

Plan B might be to buy a Seagate SCSI 15k.3 as the C: drive and back
up to an external drive.

Plan C might be to use two internal drives, SCSI or IDE, and back up
to an external drive.

Plan D could be a couple of internal SATAS -- WD Raptors, let's say --
and back up to an external drive.

Plan E might be to have multiple internal drives in a RAID array --
SCSI or IDE -- which might give me some extra performance and/or
security (I guess), but at the cost of greater complications?

So, should I Keep It Simple, or should I look into a more involved
sort of HDD subsystem? I don't mind initial complications in getting
it set up, as long as it runs reliably, easily, and FAST after I get
it set up.

Any help will be greatly appreciated!

JPD