Since it won't void your warranty, remove the cooler, clean it, then use some good T.I.M. on there. Reseat and check temps. The score seems about right for stock without tweaking any IQ settings to help inflate the score, the system I just fixed that had a AGP 6600GT@500/1000 scored nearly identical with a a64 3400+ and 2x512MB CL2 XMS. If the temp drops quite a bit, see how it overclocks. Otherwise a Zalman would definitely get it down nicely.
EDIT: Looks like digilife scored about 400points higher, with an inferior CPU and the 84.21's and that it should be a couple 100points faster than the 6600GT there. Probably just set it to high performance and get the right score since it looks like a$$.