JUST DO IT!!!!
i was going to start a whole thread, but you've given the the perfect opportunity to say...
i just upgraded today. i've got an imac se (400mhz), running OS 9.1.2. bought OSX.3.4 off ebay for £50. seller had two sets due to buying additional macs.
my only regret is not doing it sooner. i've spent all day tweaking my preferences. it's a dream. it does 'seem' a little slower on first use, but the way it all so well intergrated and smooth is a joy. it's like i've just bought a brand new G5...
and there's so much good 3rd part software. i've just found out about Xfactor. amazing.
DO IT, DO IT, DO IT, DO IT, DO IT 😀