Yep, I take about 3 hours to build a PC before it is ready to power-up. Heck, takes me about 3 minutes to get the thermal paste applied so I can mount the HSF on the CPU, as I am very careful about getting a precise layer of it spread across the face of the CPU.
And if the HSF wiggles at all while I am trying to clamp it down, I start over. It is part of the process to build a good overclocking system. Did I mention my 3.7Ghz E8400 does not break 43C under heavy loads and idles at 27C? Of course, not using the stock HSF helps.
A significant amount of time is spent doing cable manangement.
One thing I do to speed the OS install is build slipstream OS's with preconfigured answers to all the questions the normal Windows installer asks as well as all the patches already installed. Plop in the CD, then walk away and it does the complete install.
All I have to do to the slipstreamed image is change the serial key for new builds and make sure any new updates are already installed.
Takes some time to get that first slipstreamed disc built, as you have to install it to get the list of patches to grab from Microsoft, but after that, it is just a discipline to keep make sure to keep it up to date.