found this a while ago, pretty good site.
i think useing extreme amounts of tweaks is like burning in an overclock..
Too much and it'll be bad.. little bit is nice though.
Best tweak I have done so far was making a Hardware Profile choice menu upon bootup.. I have a gameing profile with 70mb memory useage, whilsts my normal profile has 200mb when nothing is running. Games run and load alot faster.