To answer your last question first, I don't trust the random number generator in my OS, let alone when used from javascript running on a liveUSB. Fortunately, bitaddress.org lets you provide your own private key which you can randomly generate from a more trustworthy source of randomness.
I was thinking about something, what are the rules for generating your own WIF 51 characters base58 private address? Is the only rule that the first character in the string is "5" ?
In that case, it would be pretty straight forward to generate your own private key.