I just got a 9800 pro too. Before that I had an FX5600, which was fine, if a bit slow. Well, I uninstalled the drivers, got rid of all the extra utils, turned off the PC, put in the new card, installed the new drivers, rebooted... and presto, error after error.
For some reason Windows was not able to write it's cache to the harddisk with the radeon drivers (tried original cd version, and newest one from ati). After trying many different things, I had to resort to a full re-format + re-install to get it to work properly.
Of course, now that I have it running, it's great. I have a 3D mark ('03) score of some 5600 points, against 2700 for my old card. If I can get the thing modded with a 9800 XT firmware (and bigger cooler), this can go up another 5 or 600 points.
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Refresh rates: for an olde CRT monitor (ye olde big birtha), you want a refresh rate over 75 or 80 hz. For a new TFT monitor, it really doesn't matter - they typically run at 60 or 75 hz, depending on the type and brand, and there's not much you can or need to do about that.