If your setup leaks, it will brick anything it touches, and maybe more. It depends on how it goes out.
You don't just refrigerate water either. First, if you freeze it somehow, you're toast because the whole thing will stop working. Second, filling tubes (and blocks) with liquid of a temperature below the dew point in your case/house will cause condensation, and so you won't even need a leak to brick your hardware that way.
If you don't plan to overclock like a madman, don't bother. Water doesn't cool everything either. Mobo needs airflow, so do hard drives, and PSU. If you are concerned about noise now, you will be after water too, even if you decide to do CPU Chipset AND GPU. What you should probably be doing is looking for a better case (Antec P180 comes to mind) with superior airflow, and quieter fans (Yate-Loons come to mind) to replace the loud ones you have now, and a top-quality air cooler for your CPU/GPU, like the Scythe Infinity (CPU), and the Zalman ZF-900 Cu (GPU). That stuff will probably put you at $200, and offer just as much performance and sound-reduction as just blindly buying some Water cooling kit.
Petra's Tech Shop has outstanding kits preconfigured. You'll need to drop at least $200 to get a good one. As I said though; you'll STILL have the issue of poor case airflow and noisy crap-fans, so you'll need to spend some cash fixing that problem even if you do decide to do water.
I'd get some quality air cooling installed before I did anything with water. That's what I did. My crap-arse Antec 1060 (they dont' even make them anymore) is quieter than my dualie G4 Mac Tower, thanks to quality air cooling. With a better case I could be even quieter, and I've got my CPU and GPU both overclocked to the gills.
I've been overclocking for 5 years now and I'm STILL not sure it's worth it to drop the extra $300 for a couple hundred mhz. Like I said - do decent air cooling before you turn to water as the answer.