When you pass a CP it comes up with the difference between your time and the WR time (and stage time difference for staged):
http://img267.imageshack.us/img267/1...2041000002.jpg
How about adding another difference there between your PR and your current time in that little display box. Something like this:
http://img407.imageshack.us/img407/1...000002copy.jpg
Or perhaps a setting or command to change the top difference against PR instead of WR so the info box doesn't get too bulky.