Quest brought the good point of Backups which I forgot.

I've looked at Tape / CD / DVD Media etc.. and the best method of backup is to buy an External USB Hard drive.   I plugg mine in.. do my backup... un-plug and store somewhere safe.   If you want more full detail why I dont like the other methods let me know.

I've worked as an I.T. Administrator in the past taking care of several servers and Raid was a life saver a few times.  Which was, overnight a hard drive had failed on an important file server.  without Raid, it would have been a day of panic and a day spent restoring data from Backup's and hoping that the backup tapes were in good order.

Since Raid system was in place, it was a matter of removing the old drive and inserting a new drive and the data from the good drives were copied onto the new drive, all this was done transparent to the network/users.

Raid might not be perfect, but its like having car insurance , you may or may not need to take advantage of it, but its there if you do need it.

Good Luck with the new computer purchase.