To understand what is happening is very sensible. The choice of operating System, though....not so good. XP-64 was kind of a trial run, and was quickly dropped. There has been no further development for two or three years, and consequently no drivers are being written today. Who knows, you might be looking at a bug right now ?
In fact, the link I give below will show you that XP professional 64 was not actually released until 2005, there has never been, nor will ever be, a service pack. Support in general is planned to finish April 2009, though security patches will continue for an unknowable time.
http://support.microsoft.com/lifecycle/?LN=en-gb&x=16&y=12&C2=1173
As to what you
should be running, obviously it depends upon what you want to use it for. It could be a server, then Windows server 2008 would be suitable, but a Linux distro would be better. Or it could be a workstation, in which case only Vista-64 makes much sense, but I personally would run 'any old thing' on it and wait for Windows 7 SP1. I would not want to spend heavily on an OS which is taking a long time to move into a usable state, when the next real OS event will be (effectively) Vista SP2, but being called Windows 7 will of course require paying for, and is unlikely to even be offered as a cheap upgrade to Vista. That is business.
I am sorry I cannot help you throw light on the actual question you wanted answering though....
http://www.acnc.com/04_01_00.html is pretty good advice concening all available RAID setups. Raid 10 (or 1+0) does not come out too well. For sheer performance RAID 5 is best. Only needs three drives at minimum. I run a Raid 5 server on netware with three SCSI drives. Nothing has failed at 8 years old (touch wood, it is still running as standby server, taking live copies daily)