A couple comments on using the time as a seed: Any system running NTP will let you know its clock to within a couple ms; some folks have gotten NTP accuracy down to the high hundred microseconds on real-time systems.. Any entropy you get from sampling the system clock will have to come from the low-order bits of the tv_usec, or equivalent, and you'll only get a few bits per sample. Getting real entropy from mouse movements under X may be tricky, because the X server goes out of its way to compress mouse movement reporting and to buffer events sent to the client ("X is an exercise in avoiding system calls"). You'll probably get less entropy than you might think.
the second 32bit seed is the "tick count", which I'm told is the number of milliseconds since windows started.
A 32-bit ms-resolution counter wraps roughly every 50 days. Very few Windoze PC's stay up that long :-). In a long-term active attack, the tick count can be estimated by periodically pinging the system under attack, noticing when it goes off the air and then back on again, and using that as a base value for the tick count search, so the tick count probably only adds a factor of somewhat less than 2**10 to the keyspace, not 2**32.. - Bill