37dBA is reasonable noise? You have a
very different concept of reasonable than I do

.
I even thought the 28dBA fan on the standard GC68 was too loud, and replaced it with a 21dBA Panaflo L1A. It cools my XP 1600+ without any problems, and that's with just a single L1A case intake fan and a single L1A case exhaust fan -- and in a Superpower case that has been referred to as an "oven" by reviewers. So I suspect the GC68 with the standard 28dBA fan should be fine with a non-overclocked XP 2000+.
Now I just need to replace the Maxtor 7200rpm hard drive in the aforementioned machine. The idle whine from that thing is like nails on a chalkboard...