At some point you are going to have to consider is this:
Raid 5 can easily handle ONE failed drive, but any more than that and it packs up. Now sure windows might be able to support 32 drives - but do you really want to risk ALL your data on all your drives in one big swoop??
At some point you are going to have to step back and say 'ok, as great as one drive sounds, its just not a viable realistic GOOD solution' and get over that.
Now consider instead you use standard SATA Raid cards - 6 drives together means that if you have 18 drives - you can have 3 seperate drives fail and the system can still keep running in best case scenario (one drive fails on each raid). Compare this to your windows setup and you can instantly see the huge advantage.
There's probably a reason they limit how many drives can go onto one RAID card and thats because no one would want to risk TOO much data all in one fell swoop - theres no reason for it. I know not a single business would do it - they'd tell their staff to get over their issues with multiple drives and just deal with it.
There is of course the other fact that you can mount drives in XP I believe as folders. You could in theory just have one as your main drive, then mount all your other drives as folders within that.
Windows can do 32 drives you say - great, windows also claims it can run stably and securely - I'm yet to see that happen and I most definitely wouldn't risk all my data on Windows claim of anything. I can just imagine windows trying to properly manage and spread data over 32 drives
"ok, now where does this 1 go, was I on drive 13 or drive 14 a min ago, that stupid svchost just distracted me for a minute and I cant remember where I was now'.
Plus your CPU will be screaming trying to split the data and write it to this many drives. With hardware windows just says 'oi raid controller, write this 500Gb file, now what was it you wanted Mr svchost" while the controller gets on with the rest.
Sure you might have to pay for some more hardware, but you know what - if your doing a project this size anyway you should expect to be doing it properly not just thinking along the lines of just only spending money on a never ending supply of drives and not having to invest in anything else.
You put 32 drives into one system that systems OS can destroy the whole lot of data, a virus on it can destroy the whole thing, the software hacked raid of the OS can destroy the whole thing.
You put 32 drives into 6 raid controlers instead and the OS can destroy the data still, but otherwise if a controller goes it only destroys 6 drives worth of data, not 32!
You split those cards into 3 systems (when I say systems I mean bare minimum - these aren't desktop computers, they're functioning boards to control stuff so you just need very low spec (and extremely cheap) motherboard, CPU, RAM - thats it, or just buy second hand old systems off ebay for next to nothing) and once you've split them into 3 systems you then have an even more secure setup - a virus hitting your OS and trashing it and deleting everything on it only takes down 1/3 of your data - the other 2/3 is completely safe still.
Instead of having to back up 52342Tb of data so you can add a new drive each time, instead you can just incrementally build up a new server box to add to the rest of your data - it can grow as you do without your current situation of having to scrap it all and start from scratch each time.
Before you start saying how expensive all these extra computers would be, a SUPER quick search of ebay finds TONS of results like this:
http://cgi.ebay.com/Dell-Optiplex-GX150-Desktop-P3-1GHz-256MB-20GB-CD_W0QQitemZ160095465377QQcategoryZ140070QQrdZ1QQcmdZViewItemjust screaming for you to make them into file servers.
I even saw some $20 machines but it just depends what spec you want your file servers to run at. Google builds their insanely huge storage infrastructure from lots of cheap machines - well I say your just as good as google and why cant you too!
Take these systems out their cases, fit them into your home made case your gonna make for all your hard drives and you could have a REALLY cool looking system:
5 drives with a motherboard screwed to the side of every 5 drives controlling them.
It wouldn't look like lots of systems, it'd look like one UBER (wow term stolen for this context) multi core AND controller computer.