To clarify my earlier post, I wholeheartedly agree that SCSI wipes the floor with IDE in terms of performance and reliability. But so does a Porsche Boxster when compared to a Camry. You get what you pay for. The real question is, do you need it? SCSI, like a Porsche, is fun to drive, and worth mucho bragging rights to anyone familliar with it. I wouldn't use anything but SCSI for my mission-critical stuff, but I don't have a need for it at home. 
Here's what I do at work:
Network Admin (Dell Poweredge server / Backoffice SBS). 15 users. Server is used as a proxy server, file server, database server, and mail server
 - 2 Quantum Atlas V's in RAID 1 (for reliability)
 - 20/40 GB U2W DDS4 Tape Drive for backups
I chose this config because:
 - Multiple users are accessing the net via a DSL line
 - I need a reliable storage system for mission critical files
 - The tape drive doesn't take a week to backup everything, nor bog the system down while doing so
 - The server has to perform multiple simultaneous operations
Here's what I do at home (WinME/2k dual boot):
 - Visit the AGN forums and Anandtech Forums
 - Gaming (Unreal Tournament, Q3A, The Sims, SoF, Zork 

 )
 - Download lots of er... files from mIRC
 - Burn lotsa CD's
 - Napster
Here my SCSI config benefits me very little, as I am not doing enough at one time to tax the system. The DMA setting on my UDMA/100 drives helps keep CPU usage down. I keep multiple IE5.5 windows open at all times, burn CD's with my BURNProof Plexwriter (using Nero), and notice 
zero performance loss over my old SCSI rig. 
As a matter of fact, I'd venture to say that this rig runs better. Why?
 - Less heat (overclocked PIII more stable at lower voltage)
 - Quicker boot times b/c of no SCSI polling
 - MUCHO Quiter (all these fast seeks you hear of? You pay for them with a god-awful noise that sounds like a toy machine gun. RAT-TAT-TAT!!!)
 - Gobs of storage on the cheap
Point being, NFS4, what exactly will you be doing, if anything, that you'll need SCSI for?
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