RAID isn't really necessary for an application like that. RAID means when you change something on the drive, you update another drive simultaneously, in real time. For your bit torrent example it's enough to just use ordinary backups, which just means rsync'ing one drive to another every so often (nightly or whatever). That is fairly fast since it only copies the new or updated files, keeping the drives in sync. That may even help reliability, since the second drive isn't spinning except when you do a backup.
Take a look at decapod-project.org for a complete system. Note that software dewarping is quite a hard problem, but it is part of decapod.
Er, what do you think Sony's "core business" is? Hint: it's not TV sets.
It sounds like you're just trying to save some server resources, not run an ultra high security operation, and that you probably DO want to let legitimate users access the site even when they're travelling. The simplest thing, it sounds like, is to just ask people to enter their zip code when they register. Explain that it's a site for a certain locality and they shouldn't register if they're not from there. If they enter an out-of-area zip code, give them an error page explaining the same thing again. Don't tell them the "valid" zip codes. Yes they could look them up if they're motivated enough, but in that case you probably want to let them in anyway, i.e. maybe they used to live there and still have connections to the area, that sort of thing.
All the stuff about IP geolocation seems like a waste of resources in this context.
In firefox 3.0.5:
Edit -> Preferences and select the "advanced" (gear) icon. From there, select the "encryption" tab. Under that tab, click "view certificates" and then "authorities". Select any CA that you want to remove and click "delete".
Yeah a lot of people are still running 32 bit OS's, but almost all desktop hardware now being shipped is 64 bit-- we're in something like the tail end of the Windows 3.x era. I think most serious users will run 64 bit OS's pretty soon. The Mac Pro uses FB-DIMM and has 8 sockets (wish it had 16) and for a big class of data crunching tasks, what matters most is the amount of ram you can throw at it. The recent collapse in ram prices has been amazing. If enough sockets were available we could fit out $5000 boxes (think of a fully loaded Dell Precision or Mac Pro, not exactly a mass market consumer pc, but not a high end Sun server either) with 128GB or maybe even 256GB. That really extends the range of problems you can attack. But, the bottleneck even in server boards seems to always be ram sockets.
I just don't understand why there aren't more consumer boards with a lot more sockets, using FB-DIMM or registered DDR. You have to go to server boards for that ($$$).
Retirement means that when someone says "Have a nice day", you actually have a shot at it.