RE: I upgraded my pc in Jan to a 1000mhz pc and now the game
Ugh.
If one PC is faster than another one then it performs the same calculations faster. That means even if you really are moving across the desert faster your PC is performing exactly the same operations as everyone else playing the game - no matter how fast or slow.
You could have a quantum computer but there's no goddamn way in hell that's going to cause it to skip bits of the program selectively and hence your hypothesis that you're getting less random encounters is, in short, utter rubbish.
I'm extremely sceptical either way because the speed of operation hasn't affected the basic game time of games since 286's came on the scene and programmers realised that they needed a way to control the blistering 8mhz speed for older PC's.