So, since there wasn't any actual cost involved, then...
If I were you I would go and install the newest ATi drivers or perhaps one of the modified ones.
Take a look at the card itself and see what HSF it is using. If its the actual standard retail one for the X1900XT then you could probably overclock it easily to the retail speeds (core speed I believe is 625, so it would give a pretty good boost to performance).
If not, then either be happy with what you got (which you look to be anyways) and go with it, or pick up an aftermarket cooler and go crazy (might be able to get to 700 core/1800 memory).