To answer your question: I ran the Horizon series solo strings and various other sample libraries from single drives attached to a Windows machine running Gigastudio and this worked fine. Then I setup an external RAID for my G5 using a Seritek SATA card and having been using it for over 3 years and it works fine.
I think that the argument over seek times of single drives vs. RAID may be a bit overdone.
For example, the published specs of the new 300GB 10,000 RPM Western Digital VelociRaptor drive claim that it has a 4.2 ms average seek (read) time and a 4.7 ms average seek (write) time. Seagate claims that the average seek times of the 1.0TB Seagate Barracuda ES-2 Enterprise-Class SATA II 7200RPM drive (reputedly a very fast drive suitable for streaming samples) are 8.5ms (read) and 9.5 (write).
Thus the VelociRaptor is, in terms of claimed seek times, more than twice as fast as the Seagate 1.0 TB drive - - - a vastly larger difference than the .2ms difference noted in the tests I referred to between single drive and RAID array seek times. So if you think that you must absolutely have the fastest seek times, you have to go with multiple VelociRaptors (or for more money some 15,000 RPM SAS drives). But, in reality, to stream samples, multiple VelociRaptors are very likely overkill. The folks at VSL claim that a single 1.0 TB Seagate or Samsung drive can be used to stream the whole Cube.However, tests show that a RAID 0 array has faster I/O per second on file sizes from 1K to 32K - as well as on larger size files.
In addition to the fact that the WD VelociRaptor costs $300 for 300 GB (whereas the Seagate Enterprise class 1.0 TB drive costs $250-300), it has the drawbackof a non-standard design ((because it is based on a 2.5" drive rather than a 3.5" drive), so it won't connect to normal 3.5" backplanes like those in the MacPro - - or any 3.5" enclosures with drive trays. It will only work in situations where it connects via SATA cables (e.g. in a fixed bay within a PC, a fixed bay external enclosure or, if you are a MacPro user, some non standard, home-made, rig inside a MacPro + cables to the two unused SATA ports on the MacPro motherboard). I wrote to Western Digital asking if they planned to release a version of this drive that would mate with normal 3.5" backplanes and they said they "couldn't comment on non-existent products." Whatever that means! (Perhaps it's simply another triumph of intelligent industrial design to make a super fast drive that will not mate with the standard backplanes most users would want to use it with?)
Several reviews of new Samsung drive 1.0 TB drive have found that it is currently the fastest 1.0 TB SATA drive. However, if you go to Newegg.com and read the customer reviews of this drive, you find many customers claiming that their drives arrived DOA or died soon after installation. So this might give one pause. I have no idea if these reviews are representative or not, nor do I have any idea of how good Samsung customer support is. In light of this, Seagate, at present, seems, to me, a possibly safer bet. However, you might try calling Other World Computing and talking to them about this as they are knowledable and they have just started selling Samsung drives. I doubt they would sell any product that gets returned frequently.