If you want to build your own PC, I would recommend installing a GNU/Linux distro.
A self-built PC with a good looking GNU/Linux distro with some fancy Beryl/Compiz stuff is awesome... and much fun to build
Yep! I have done just that recently. I was delving back into some older technology. So far, I have built two:
1/ A *dual core* Pentium Pro 200 machine. I loaded Windows NT and Arch Linux 2007 onto it. For a 200 MHz machine (or 400 MHz, if you sum the two CPUs), it is darn snappy. I did this one just for fun and nostalgia. I loved my old 200 MHz Micron machine when it was in it's prime, and decided to recreate it, but only better... hence the dual CPUs. Loading Linux was a real bonus too.
2/ After that experience, I decided to build a nearly current machine, but still a few years behind the bleeding edge, to keep costs low. I built a 3.06 GHz Pentium IV HT machine with 1 GB of PC 1066 RDRAM (RAMBUS stuff -
F-A-S-T), 240 GB of hard drive, the fastest AGP video card that was made (nVidia GeForce 7800GS), ZIP-250, CD-RW, DVD-RW, 10/100 NIC and lots of other little goodies. I loaded Windows ME and openSUSE 10.3 on it. openSUSE 10.3 is simply amazing. The best Linux distro I have ever used, bar none.
The best thing about these two machines is that as the system architect, I was able to design them from the ground up as "quiet computers". Every part has been selected with careful consideration of its noise profile. The net result is that the Pentium Pro 200 machine is essentially silent. The 2.06 GHz machine is nearly as quiet, although you can hear a gentle swoosh from the graphics card fan (I didn't replace the stock cooler that came with it).
Lots of fun, and I really enjoyed tinkering with it. In the end however, here I am, cranking away on my Mac. It is hard to beat the total experience that Apple puts together, even when you can control every element of the solution yourself.